US3703889A

US3703889A - Ignition arrangement for internal combustion engines

Info

Publication number: US3703889A
Application number: US83039A
Authority: US
Inventors: Bernd Bodig; Gerhard Sohner; Gert Strelow
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1969-10-31
Filing date: 1970-10-22
Publication date: 1972-11-28
Anticipated expiration: 1989-11-28
Also published as: GB1291749A; SE358447B; FR2066785A5; CS153565B2; DE1954874A1; ES385049A1; JPS4929213B1; DE1954874B2; DE1954874C3

Abstract

Four rotating magnets, driven by the engine, induce in two or more windings a charging pulse, a discharging pulse, and a control pulse, the latter pulse in certain embodiments being identical with the charging pulse. The control pulse, the value of which is engine rpm-dependent, causes a normally open circuit shunting the ignition capacitor to close when the engine rpm exceeds the permissible maximum, thereby discharging the ignition capacitor and preventing it from furnishing electrical energy to the spark coil. In this way, the engine rpm is limited to safe values.

Description

United States Patent Bodig et al. Nov. 28, 1972 [5 IGNITION ARRANGENIENT FOR 3,461,851 8/1969 Stephens ..123/ 148 E INTERNAL COMBUSTION ENGINES 3,464,397 9/1969 Burson 123/ 148 E [72] Inventors: Bernd Bodig, Leinfelden; Gerhard f: snehw 3,504,373 3/1970 Strelow ..123/148 E g y 3,515,109 6/1970 Farr ..l23/148 E [73] Assignee: Robert Bosch Gmbl-l, Stuttgart, Ger- 3,534,719 10/1970 Minks 123/148 E many 3,545,419 12/ 1970 Nolting ..123/148 E [22] Filed: od- 22, 1970 3,545,420 12/1970 Foreman ..123/148 E [21] Appl. No.: 83,039 Primary Examiner-Laurence M. Goodridge Assistant Examiner-Rona.ld B. Cox [30] Foreign Application Priority Data Attorney Mlchael Striker Oct. 31, 1969 Germany ..P 19 54 874.4 [57] ABSTRACT Four rotating magnets, driven by the engine, induce in [52] 145 ggfigg two or more winding a charg n Pulse, a dischargin 51 lm. c1 ..F02p 9/00, F02p 1/00, F02p 77/00 pulse a l f" pulse 3 58 Field of Search 123/102 148 E 118 198 DC emmmems bemg the chargng Pulse The control pulse, the value of which is engine rpmdependent, causes a normally open circuit shunting [56] References cue! the ignition capacitor to close when the engine rpm UNITED STATES PATENTS exceeds the permissible maximum, thereby discharging the ignition capacitor and preventing it from 3,563,219 2/1971 M1ekas ..l23/148 E furnishing electrical energy to the spark coil. In this 3,581,720 6/ 1971 l-lemphlll ..123/148 E way, the engine rpm is limited) Safe values 3,367,314 2/1968 l-lirosawa ..123/148 E 3,398,353 8/1968 Noddin ..123/148 E 36081115, 10 Figures PAlENTEuunvza'lsrz 3.703.889

SHEET 1 UF 5 FIGJ FIG.2 K K \ZJ46 ms' lw 47 INVENTORS Bernd BQDIG Gerhard SOHNER Gert STRELOW their ATTORNEY FIG.3

INVENTORS Bernd BODJG Gerhard SOHNER Gert STRE LOW their ATTORNEY Pmiminnuv 3.703.889

SHEET 3 BF 5 FIG.6

INVENTORS Bernd BQDIG Gerhard SOHNE-IR I Gert STRE LOW r/ I", 1 their ATTORNEY PATENTEDN 3.703.889

SHEET u 0F 5 INVENTORS Bernd BQDIG Gerhard SOHNER' Gert STRELOW B //i// y/ Z their ATTORNEY PATENTED Nov 2 8 I972 SHEEI 5 OF 5 INVENTORS Bernd BQDIG 4 Gerhard SOHNER Gert STRELOW their ATTORNEY IGNITION ARRANGEIVIENT FOR INTERNAL COMBUSTION ENGINES BACKGROUND OF THE INVENTION The invention relates to an ignition arrangement for internal combustion engines.

It sometimes occurs during operation of an internal combustion engine that parts of the engine sufi'er costly, and even irreparable, damage, because of extreme loads caused by excessive rpm.

SUMMARY OF THE INVENTION An object of the invention is an ignition arrangement for internal combustion engines that provides an inexpensive solution to the problem of automatically limiting the speed of an engine to safe values. I

The invention consists essentially of at least one spark plug, an ignition capacitor for storing energy and arranged to cause, when discharged, sparking of the spark plugs, winding means connected to the ignition capacitor, movable magnet means driven by the engine at a speed proportional to the speed of the engine and inducing in the winding means periodically a sequence of pulses, namely, a charge pulse charging the ignition capacitor, a control pulse the value of which is proportional to the engine speed, and a discharge pulse causing discharge of the ignition capacitor, normally open electronic switch means actuated by the control pulse induced in the winding means for closing the electronic switch means when the engine speed exceeds a predetermined value, the normally open switch means being connected in series with the ignition capacitor so as at least to prevent the ignition capacitor from being charged to a voltage sufficient to cause sparking of the spark plug when the control pulse is induced in the windings.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a circuit diagram of the basic embodiment of the invention;

FIG. 2 shows the curves of the induced charge and discharge voltages;

FIGS. 3, 4, and 5 show three additional embodiments of the invention;

FIG. 6 shows the curves of the charge and control voltages induced in the windings of the embodiment shown in FIG. 5; and

FIGS. 7-10 show four further embodiments of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to FIG. 1, the ignition arrangement of the invention comprises an ignition capacitor 1 l, which is charged with the electrical energy for the spar. The capacitor terminal 12, which is the positive terminal of the charged capacitor 11, is connected to the cathode of a charging diode 13, the anode of which is connected to one end 14 of a charge winding 15. The other end 16 of this winding is connected to the terminal 17 of the ignition capacitor 11, this latter terminal being negative when the capacitor is charged. Connected across the output of the charge winding 15 is a voltage-dependent resistor 18, which protects the charging diode 13 against overload. A diode 19, which prevents reverse charging of the ignition capacitor 11, has its cathode and anode respectively connected to the positive terminal 12 and the negative terminal 17 of the capacitor 11.

The positive terminal 12 is also connected to the anode A of an electronic switch 20, comprising a thyristor of which the cathode K is connected to one end 21 of the primary winding 23 of a spark coil 22. The other end 24 of this primary winding is connected to the negative terminal 17 of the capacitor 11 and also to the. grounded terminal 25.

The spark coil 22 further comprises a secondary winding 26 of which one end 27 is connected to one terminal of a spark plug 28 and of which the other end 29 is connected both to the other terminal of the spark plug 28 and also to the grounded terminal 25 The spark coil 22 also has a shorted winding, which prevents the ignition timing adjustment from assuming unreasonable values.

Discharge means in FIG. 1 comprises thyristor 20 which is operative for efiecting firing of spark plug 28 upon receipt of an ignition signal from winding 23 by transmitting to the spark plug the energy stored in capacitor 1 1. Also, discharge circuit means 20 serves to provide a discharge path for the capacitor 11 without effecting firing of spark plug 28 upon receipt from winding 23 of a conn'ol signal having a predetermined threshold value.

The thyristor, which forms the discharge switch 20, has a control electrode S, which is connected to the cathode K of the thyristor by a resistor 31 that determines the switching threshold. Shunted across the resistor 31 is a capacitor 32 for bypassing interference pulses. A control resistor 33, which can be adjustable, is connected between the control electrode S and the cathode of a control diode 34, the anode of which latter is connected to the grounded terminal 25. In the present embodiment, the control signals for triggering the thyristor are delivered by the primary winding 23 of the spark coil 22. The control signals have said predetermined threshold value when the speed of crankshaft 44, and therefore of the engine, has risen to a predetermined value. An arrangement of magnets 35 induces voltages in both the charge winding 15 and the spark coil 22.

The charge winding 15 is wound on an iron core 36, which is constructed in the manner of a chord-type armature. The primary winding 23, the secondary winding 26, and the shorted winding 30 are wound on a common iron core 37, which is also constructed in the manner of a chord-type armature. The two

cores

36 and 37 are fixed to a stationary plate 38 made of a nonmagnetic material. The magnet arrangement 35 consists of four

permanent magnets

39, 40, 41, and 42 which are arranged along the circumference of a rotated disk 43. This disk is fixed to the crankshaft 44 of an internal combustion engine, not shown. As the disk 43 rotates, the

magnets

39, 40, 41, and 42 move in the direction D past the ends of the

iron cores

36 and 37. Of these four magnets three (39, 40, 41) face the

cores

36 and 37 with the same pole (in the present example, the south pole), and one (42) faces these cores with the opposite pole (in the present example, the north pole). These four magnets are equally spaced along the circumference of the disk 43, so that the spacing X is always the same between the ends of neighboring magnets. The dimensions of the

cores

36 and 37 are such that, in a given rotational position of the disk 43, the ends of the same core at least approximately face the spacings X at the two ends of the same magnet, as shown in FIG. 1.

The voltage pulses induced in the charge winding and in the primary winding 23, when the magnet arrangement 35 rotates, are shown in the voltage/time diagram, FIG. 2. The chargingpulse or signal is the positive half-wave 45, and the control pulse is the positive half-wave 45 The two negative half-

waves

46 and 47 or 46 and 47 are blocked respectively by the charging diode l3 and the control diode 34.

The following analysis will facilitate understanding of the operation of this embodiment.

Arbitrarily considering ground to be at zero" volts, it will be appreciated, then, that

points

17, 25, 24 and 29 will be permanently fixed at zero volts, regardless of the voltage across capacitor 11, and regardless of any other circuit condition; i.e., the-voltage at

points

17, 25, 24, 29'is considered fixed at zero, as a point of reference.

Assuming now, that capacitor 11 is charged, point 12 will be positive with respect to point 17; i.e., point 12 will be at some positive voltage,-and point 17 at zero volts. When control signal 45' appears across coil 23, the voltage at point 24 will be positive with respect to point 21. However, point 24 is at zero volts (ground), so that point 21 must be at a negative voltage.

Now, consider the situation with switch off and on. When switch 20 is off, it is in effect an open circuit. Thus, there will exist two independent circuits sharing a common ground; one such circuit is formed by

elements

34, 33, 31, 23; the other, completely independent circuit, is formed by

elements

15, 18, l3, 19, 11. Inasmuch as these circuits are independent, the voltage on capacitor 11 will not neutralize any voltage in the other circuit.

When switch 20 conducts, (due to FIG. 1 to control signal 45 appearing on coil 23), then the circuits are no longer independent; i.e., certain currents will pass through both of the circuits.

With switch 20 conducting, coil terminal 21 will be at a negative voltage with respect to zero-volt terminal 24. Point K will be at this same negative voltage. This is proper. Thus, point K will be negative with respect to positive point 12, so that current flows from A to K. Point K will be negative with respect to point 25, so that current flows through diode 34 and then resistor 31. As a final check, it will be noted that with such current flowing through resistor 31, point S will be positive with respect to point K, and this of course is the condition-for the switch 20 to be in conductive condition. When the magnet 42 moves past the iron core 36 there is induced in the charge winding 15 a voltage that varies approximately in the manner shown in FIG. 2. During the positive half-wave 45, the ignition capacitor 1 1 is charged through the charging diode 13. After the ignition capacitor 11 is charged, there is sufficient electrical energy stored to spark the plug 28. As the magnet 42 moves past the iron core 37 there is induced in the primary winding 23 a voltage, the form of which is approximately shown in FIG. 2. Only the positive halfwave 45, which is the control signal or pulse, is conducted through the control diode 34 and the control resistor 33 to the control electrode S of the electronic discharge switch 20. Since the control electrode S consequently becomes positive with respect to the cathode K, the anode-cathode path A-K is rendered conductive, permitting the ignition capacitor 11 to discharge through the switching path A-K and the primary winding 23. Consequently, there is induced in the secondary winding 37 a high-voltage pulse that causes the plug 28 to spark. I

Unless measures to the contrary are taken, the rpm of the internal combustion engine will rise to some value that under certain conditions can be so high that parts of the internal combustion engine are damaged and even destroyed. In accordance with the invention, this is avoided by generating an rpm-dependent control voltage that closes an electronic switch which is shunted across the ignition capacitor 11 and prevents the capacitor from charging, or at least from charging to a value sufficient to spark the plug 28 when the discharge pulse is conducted to the control electrode S. This rpm-dependent control voltage can be conducted to the control electrode S of the discharge switch 20. The shunt circuit thus closed leads from the positive terminal 12 of the ignition capacitor, through the nowconductive anode-cathode path A-K and the primary winding 23, to the negative terminal 17 of the capacitor 11. In this embodiment, both the charging pulse and the control signal can be induced in the primary winding 23 by the rotating magnet arrangement 35. It is es sential, however, that of the three magnets (39, 40, 41) having the same pole (the south pole) facing the

cores

36 and 37, the center magnet 40 must have a weaker field than the

magnets

39 or 41.

When the magnet 40, with the weaker field, passes by the core 37, a voltage is induced in the primary winding 23 by the change in flux associated with weaker magnet 40, the value of this voltage increasing with rising rpm. In this embodiment, this voltage is used as the control signal, the value of which is so determined by suitable choice of the magnet 40 (which determines the strength of the magnetic field of this magnet) that when the engine rpm exceeds the permissible maximum, it triggers the anode-cathode path A-K. The triggering occurs when the charge winding 15 supplies charging current to the ignition capacitor 11. The charging current is immediately conducted through the shunt circuit, composed of the path A-K and the primary 23, so that the capacitor 11 cannot charge and can not furnish electrical energy for sparking the plug 28 when the discharge pulse is conducted to the control electrode S. This series of events repeats itself so long as the rpm of the internal combustion engme is excessive.

The action of the weaker magnet 40 can be understood more clearly by considering the following.

The various windings in the generator have such orientation that when north-pole magnet 42 passes coil it will generate thereacross the charging pulse. Later, the same magnet 42 will pass by

coils

23, 26 and produce the ignition signal.

The winding orientations are such that south-

pole magnets

39, 40, 41, if equal, could not produce a proper-polarity pulse in either of

coils

15 or 23. Specifically, if all south-pole magnets were equal, then when a south-pole magnet passed coil 23, it would not induce a pulse of polarity such as to render switch conductwo.

But with magnet 40 weaker, the situation is different. Now, as the south-pole end of the magnet system moves past coil 23, the change in field strength associated with magnet 40 will produce a control signal of polarity such as could render switch 20 conductive, if of sufficient magnitude. What determines this magnitude, assuming the magnet strengths are fixed, is the speed of the engine. Thus, if the speed and magnitude of the control signal are high enough, switch 20 is made conductive during the charging-up period of capacitor 11, limiting or eliminating the accumulation of charge on the capacitor.

Thus, when the ignition signal is induced in winding 23 by magnet 42 passing thereby, the capacitor 11 will not be sufficiently charged to produce sparking of the spark plug.

As shown in FIG. 3, it is also possible to impress the control voltage across a series-connected capacitor 48 and resistor 49. Better adjustment of the circuit can be obtained by making the resistor 49 adjustable. If necessary, a fixed resistor 50 can be connected in series with the resistor 49. The junction 51 between the capacitor 48 and the resistor 49 is connected by a lead 52 to the control electrode S of the thyristor discharge switch 20.

. To insure positive triggering of the anode-cathode path A-K when the engine speed exceeds the permissible maximum, a switch 53 is advantageously connected in the lead 52, this switch becoming conductive when the voltage across it exceeds a predetermined value. In the present embodiment, a diac 54 is used, although a zener diode 55, shown with its leads in broken lines, also gives satisfactory results, the anode of the diode being connected to the control electrode, S and the cathode to the junction 51. The condenser end of the series-connected capacitor 48 and resistor 49 is connected to the positive terminal 12 of the ignition capacitor 11, and the resistor end of this series combination is connected to the negative terminal 17 of the capacitor. Aside from the features just described, and the fact that all four magnets of the magnet arrangement 35 have fields of equal strength,-the circuit shown in FIG. 3 is the same as that shown in FIG. 1. Consequently, only as much of the embodiment of FIG. 3 is shown as is necessary to explain its operation. In all of the embodiments of the invention, those components having the same function are denoted by the same reference numerals, and will not be further described.

The embodiment shown in FIG. 3 operates in the following manner. In this embodiment the control signal is the same as the half-wave charging pulse 45 (see FIG. 2), which is induced in the charge winding 15 and used to charge the ignition capacitor 11. Thus, the same voltage is impressed across the series-connected capacitor 48, resistor 49, and resistor 50 as across the capacitor 11. As the engine rpm increases, the pulses 45 become more and more positive until the junction 51 is so positive, when the engine rpm exceeds the allowable maximum, that the voltage-dependent switch 53 becomes conductive, permitting current to flow through the control path S-K of the thyristor switch 20, through the primary 23, and back to the junction 57. Consequently, the anode-cathode path A-K becomes conductive, because at the same time the charging pulse induced in the winding 15 is impressed across the ignition capacitor 11. The charging current immediately flows through the shunt circuit composed of the path A-K and the winding 23. The ignition capacitor does not store any electrical energy, and when the discharge pulse, for the control electrode S, is induced in the primary 23, no energy is furnished to this latter winding for sparking the plug 28. These events are repeated so long as the engine rpm is excessive.

FIG. 4 shows an embodiment in which an auxiliary switch 58, composed of a thyristor and triggered by the control signal, is shunted across the ignition capacitor 11. This shunt circuit, which also comprises an auxiliary, series-connected, resistor 59, provides a current path from the negative terminal 17 of the capacitor 1 1 to the positive terminal 12 of this capacitor. Aside from these details, and aside from the fact that the lead 52 is connected to the control electrode S of the auxiliary thyristor switch 58 and not to the control electrode S of the discharge switch 20, the circuit of FIG. 4 is similar to that of FIG. 3. The advantage of the auxiliary discharge switch 58 is that the adjustment of the discharge pulse, which triggers the switch 20, is not disturbed by the circuit components across which the control pulse is impressed. In particular, discharge means in FIG. 4 includes a switch 20 for effecting firing of the spark plug upon receipt from winding 23 of an ignition signal by transmitting the energy in capacitor 1 1 to the spark plug. The FIG. 4 discharge circuit means also includes switch 58 which provides a discharge path for capacitor 11 without effecting firing of the spark plug upon receipt from winding 15 of a control signal having a predetermined threshold value.

The four magnets of the magnet arrangement 35 have the same field strength, and in all other respects, except those previously noted, the circuits of FIGS. 3 and 4 are the same.

The embodiment shown in FIG. 4 operates in the following manner. The positive charging pulse 45 (see FIG. 2), which is induced in the charging winding 15 and impressed across the capacitor 11, is again used to obtain the control voltage. Thus, the voltage across the series-connected capacitor 48, resistor 49, and resistor 50 is the same as that across the ignition capacitor 11. When the maximum allowable engine speed is exceed, the voltage-dependent switch 53, which can be either a diac 54 or a zener diode 55, becomes conductive, permitting a control current to flow through the control path S'-A and the switch 53. Thereby, the anodecathode path A'-K is triggered, because at the same time the charging pulse is impressed across the ignition capacitor 11. The charging current immediately flows through the shunt circuit, composed of the resistor 59 and the anode-cathode path A'-K'. Since the ignition capacitor cannot store any electrical energy, when the discharge pulse, for the control electrode S, is induced in the primary 23, too little energy is fumishedto this latter winding for sparking the plug 28. These events are repeated so long as the engine rpm is excessive.

FIG. shows an embodiment in which the control signals are induced in a separate control signal winding 60, which is wound on the same iron core 36 as is the charge winding 15. FIG. 6 shows in solid line the curve of the control voltage induced in the winding 60 by the magnet arrangement 35. The broken line shows the voltage induced in the charging winding 15. Of the two positive half-

wave pulses

61 and 62, only the latter, which occurs after the half-wave charging pulse 45, is actually used for controlling the switch 58, although both of the

pulses

61 and 62 charge the capacitor 48. The positive half-wave pulse 61 is without consequence, because the ignition capacitor 11 not yet being charged when it occurs the anode A of the switch 58 lacks the necessary voltage to trigger the thyristor. The half-wave pulse 63, because it is negative, can not trigger the switch 58.

Experiments have shown that the separate-control pulse winding 60 enables a very exact setting of the maximum allowable engine rpm.

The circuit shown in FIG. 5 differs from that shown in FIG. 4 only in that the condenser end 56 of the series-connected capacitor 48 and resistor 49 is connected to one end 64 of the control signal winding 60, the other end 65 of this winding being connected both to the cathode K of the thyristor auxiliary discharge switch 58 and to the resistor end 57 of the series-connected capacitor 48 and resistor 49.

The four magnets of the magnet arrangement 35 have the same field strength. In all respects, except those previously noted, the circuits of FIGS. 4 and 5 are the same.

The embodiment shown in FIG. 5 operates in the following manner. The voltage at theiiunction 51, which is dependent on the peak amplitude of the control pulses 62, becomes increasingly positive with respect to the resistor end 57 and to the cathode K, as the engine rpm rises. When the rpm exceeds the permissible maximum, the potential at the junction 51 is so positive that the switch 53 becomes conductive, permitting a control current through the control path S'-K' of the auxiliary discharge switch 58. Since the ignition capacitor 11 at this moment is already charged and its voltage is impressed across the anodecathode path A'-I( of the switch 58, this latter path is triggered, permitting the ignition capacitor 11 to discharge through the anodecathode path A'-K' and the resistor 59. When the ignition signal, for the control electrode S, is induced in the primary 23, the capacitor 11 furnishes no energy to this latter winding for sparking the plug 28. These events are repeated so long as the engine rpm is excessive.

In the embodiment shown in FIG. 7, a separate control signal winding 60 is again wound on the iron core 36. The voltages induced in the charge winding and the control signal winding 60 are shown in FIG. 6, in broken and solid lines, respectively.

The circuit shown in FIG. 7 differs from that shown in FIG. 5 in that the series circuit composed at least of the capacitor 48 and the resistor 49 is connected at its condenser end 56 with the cathode of the thyristor discharge switch and at its resistor end 57 by a voltage-dependent switch 66 (either a zener diode, as shown, or a diac) to the control electrode S of the switch 20; that the junction 51 is connected by a diode 67, which conducts only the positive half-

wave pulses

61 and 62, to the end 64 of the control signal winding and that the other end 65 of this winding is connected through the primary winding 23 to the cathode K of the switch 20. In this embodiment, the ignition capacitor 11 has no separate shunt circuit, composed of the resistor 59 and the auxiliary discharge switch 58, as does the embodiment shown in FIG. 5. The cathode and anode of the zener diode. of the switch 66 are respectively connected to the resistor 49 and the control electrode S.

The four magnets of the magnet arrangement 35 have the same field strength. In all other respects, aside from those previously noted, the circuits of FIGS. 5 and 7 are the same.

The embodiment shown in FIG. 7 operates in the following manner. Both of the positive half-

wave pulses

61 and 62, induced in the control signal winding 60 and conducted through the diode 67 and the primary 23, charge the capacitor 48 to a voltage dependent on the engine rpm. When the maximum permissible rpm is exceeded, the voltage across this capacitor is so high that the switch 66 is rendered conductive. The discharge of the capacitor 48, which follows the charging by the half-wave pulse 61, causes a current to flow through the resistor 49, the switch 66, and the control path S-K of the switch 20. The anode-cathode path A-K is consequently triggered, because at the same the charging pulse 45 is induced in the winding 15. The charging current immediately flows through the primary winding 23. Since the ignition capacitor 11 cannot store any electrical energy, when the ignition signal of the control electrode S, is induced in the primary 23, no energy is fumished to this latter winding for sparking the plug 28. These events are repeated so long as the engine rpm is excessive.

In the embodiment shown in FIG. 8, the ignition capacitor 11 is once again shunted by an auxiliary discharge switch 58 connected in series with a resistor 59, as in the embodiment shown in FIG. 5. The four magnets of the magnet arrangement 35 all have the same field strength.

The circuit shown in FIG. 8 differs from that shown in FIG. 7 in that the capacitor end 56 of the series circuit composed at least of the capacitor 48 and the resistor 49 is connected to the cathode K of the thyristor auxiliary discharge switch 58 and the resistor end 57 is connected by a voltage-dependent switch 66 to the control electrode S'. of the switch 58.

In contradistinction to the previous embodiment, when the engine rpm exceeds the permissible value, the switch 66 becomes conductive, permitting the capacitor 48 to discharge through the control path S'-K', thereby rendering the anode-cathode path A'-K' conductive. As in the previous embodiment, the charging current is bypassed through the shunt circuit, composed of the resistor 59 and the anode-cathode path A'-K. Since the ignition capacitor cannot store energy, when the ignition signal, for the control electrode S, is induced in the primary 23, no energy is furnished to this latter winding for sparking the plug 28. These ,events repeat themselves so long as the engine rpm is excessive.

In the embodiment shown in FIG. 9, a control signal winding 68 is wound on a separate control signal core 69. With respect to the axis about which the magnet arrangement 35 rotates, the core 69 lies in the projection of the core 36. In other words, the

cores

36 and 69 are aligned in the axial direction of the magnet arrangement 35. Those half-wave pulses induced in the winding 68 are control signals that are in phase with the charging half-waves 45 (see FIG. 2), which latter are induced in the charge winding 15. i

A load, or voltage-setting, resistor 70, which is preferably adjustable, is connected by its

terminals

71 and 73 to the respective ends 72 and 74 of the control pulse winding 68. A switch 75, which becomes conductive when at least a predetermined minimum voltage is impressed across it, is connected between the load resistor terminal 71 and the control electrode S of the thyristor discharge switch 20. In this embodiment, the voltage-dependent switch 75 is a diac 76, although the switch can also be a zener diode 77, the leads of which are shown in broken line, the anode and cathode of the diode being respectively connected to the control electrode S and the load resistor terminal 71. The spark coil primary winding 23 connects the load resistor terminal 73 to the cathode K of the switch 20.

The four magnets of the magnet arrangement 35 have the same field strength. In all other respects, except those previously noted, the circuit of FIG. 9 is the same as that of FIG. 1.

The embodiment shown in FIG. 9 operates in the following manner. As the engine rpm rises, the peak amplitude of the positive half-wave induced in the control signal winding 68 increases, raising the voltage across the load 70. When the engine rpm exceeds the permissible maximum, the switch 76 is rendered conductive, permitting a control current to flow through the control path S-K and the primary winding 23. Consequently, the anode-cathode path A-K is triggered, the charging pulse 45 (see FIG. 2) at the same time being induced in the charge winding 15. The charging current that normally would charge the capacitor 11 instead flows through the primary winding 23. Since the ignition capacitor cannot store any electrical energy, when the'discharge pulse, for the control electrode S, is induced in the primary 23, no energy is furnished to this latter winding for sparking the plugs 28. These events are repeated so long as the engine rpm is excessive.

In the embodiment shown in FIG. 10, the ignition capacitor 1 1 is once again shunted by a series-connected resistor 59 and auxiliary discharge switch 58, the latter being composed of a thyristor. The four magnets of the magnet arrangement 35 have the same field strength.

The terminal 71 of the voltage-setting resistor 70 is connected by the voltage dependent switch 76 to the control electrode S of the auxiliary discharge switch 58. Aside from the foregoing details, the circuit shown in FIG. is similar to that shown in FIG. 9.

In contradistinction to the previous embodiments, when the engine rpm exceeds the permissible maximum, the consequently conductive switch 75 permits a control current through the control path S-K, rendering the anode-cathode path of the thyristor conductive and thereby effectively shorting the ignition capacitor 1 1. Since the ignition capacitor cannot store electrical energy, when the ignition signal, for the control electrode S, is induced in the primary 23, no energy is furnished to this latter winding for sparking the plug 28. These events are repeated so long as the engine epm is excessive.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of circuits differing from the types described above.

While the invention has been illustrated and described as embodied in ignition arrangements for combustion engines, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit of the present invention and,- therefore, such modifications are intended to be comprehended within the range and equivalence of the following claims.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can be applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meanings and range of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

We claim:

1. In an internal combustion engine, a speed-limiting ignition arrangement comprising at least one spark plug; an ignition capacitor; first means for generating charging signals and ignition signals timed in synchronism with the rotation of said engine, and including means for generating a control signal preceding the respective signal when the speed of said engine ex ceeds a predetermined value; discharge means for effecting firing of said spark plug upon receipt of an ignition signal by permitting transmission to said spark plug of energy stored in said capacitor, and including additional means operative upon receipt of said control signal for preventing said capacitor from being in charged condition during generation of the respective subsequent ignition signal.

2. An arrangement as defined in claim 1, wherein said discharge means comprises electronic switch means for alternatively permitting and preventing flow of discharge current from said capacitor as a function of said ignition and control signals.

3. An arrangement as defined in claim 2, wherein said first means comprises movable magnet means and winding means.

4. An ignition arrangement as defined in claim 3, including stationary magnetic core means for said winding means, and wherein said movable magnet means includes four permanent magnets of which three have the same pole facing said magnetic core means and the fourth has the other pole facing said magnetic core means.

5. An ignition arrangement as defined in claim 4, wherein said winding means includes a charge winding connected with and supplying charging current to said ignition capacitor, and an ignition signal winding, said magnet means inducing a voltage across said charge winding and an ignition signal across said ignition signal winding, said core means including two magnetic cores, one for said charge winding and another for said ignition signal winding, each of said cores having two ends, said four magnets defining the perimeter of a circle and being equidistantly spaced along said perimeter, said four magnets further being so positioned relative to said two cores that said two ends of a core face the respective spaces between consecutive ones of said four magnets for a particular relative position between said four magnets and said two cores.

6. An ignition arrangement as defined in claim 5, wherein said electronic switch means includes a thyristor rendered conductive by said control signal, and one end of said ignition signal winding is connected to the cathode of said thyristor, and further including a diode connected between the other end of said ignition signal winding and the control electrode of said thyristor to conduct only positive signals.

7. An ignition arrangement as defined in claim 5, wherein said winding means further includes a control signal winding in which said control signal is induced by said magnet means, said control signal winding being wound on that one of said two magnetic cores on which said charge winding is wound.

8. An ignition arrangement as defined in claim 7, wherein said first means generates said control signal subsequent to commencing charging of said ignition capacitor.

9. An ignition arrangement as defined in claim 3, wherein said winding means includes a control signal winding in which said control signal is induced by said magnet means, and further including a stationary'control signal magnetic core for said control signal winding, and core means for the rest of said winding means.

10. An ignition arrangement as defined in claim 9, wherein said movable magnet means rotates about an axis, and said core means further includes a stationary charge magnetic core for said charge winding, said control signal and charge pulse magnetic cores being aligned in the direction defined by said axis.

11. An ignition arrangement as defined in claim 10, wherein said first produces said control signal at the same time that it begins to charge said ignition capacitor.

12. An arrangement as defined in claim 1, wherein said first means is operative for supplying charging current to said capacitor during a predetermined part of an ignition cycle, and is operative for producing said control signal during the same part of a control cycle, whereby if said control signal has said discharge circuit value said discharge circuit additional means will prevent charging of said ignition capacitor by said first means.

13. An arrangement as defined in claim 1, wherein said discharge means comprises one discharge path including an electronic switch responsive to said ignition signal, and wherein said additional means includes another discharge path including an electronic switch responsive to said control signal.

14. An arrangement as defined in claim 1, wherein said discharge means and additional means together comprise a single discharge path including electronic switch means responsive to both said ignition and control signals. 1

15. An ignition arrangemiitas defined in claim 3, wherein said electronic switch means includes a thyristor rendered conductive by said control signal and said winding means includes a spark coil having a primary connected in series with the anode-cathode path of said thyristor, said series-connected primary and anode-cathode path being connected in parallel with said ignition capacitor.

16. An ignition arrangement as defined in claim 3, wherein said electronic switch means includes a thyristor rendered conductive by said control signal, and a resistor means in series with said thyristor, said thyristor and resistor being connected in parallel with said ignition capacitor.

17. An ignition arrangement as defined in claim 3, wherein said winding means includes a common winding in which said control and ignition signals are induced.

18. An ignition arrangement as defined in claim 17, wherein said winding means includes a spark coil for said spark plug said spark coil having a primary which is said common winding.

19. An ignition arrangement as defined in claim 6, including a resistor in series with said diode.

20. An ignition arrangement as defined in claim 6, wherein of said three permanent magnets the middle one has a weaker field than the others of said four permanent magnets.

21. An ignition arrangement as defined in claim 3, including a series-connected capacitor and resistor connected to said winding means so that at least part of said control signal appears at least across one of said series-connected capacitor and resistor.

22. An ignition arrangement as defined in claim 21, wherein said resistor at least in part is an adjustable resistor.

23. An ignition arrangement as defined in claim 22, wherein said resistor consists also of a fixed resistor connected in series with said adjustable resistor.

24. An ignition arrangement as defined in claim 21,

including normally non-conductive voltage-operated switch means connected to the junction between said series-connected capacitor and resistor and to said electronic switch means for rendering the latter conductive when the engine speed exceeds a predetermined value, said voltage-operated switch means becoming conductive when the voltage at the junction exceeds a predetermined value.

25. An ignition arrangement as defined in claim 24, wherein said electronic switch means includes a thyristor rendered conductive by said control signal, and said winding means includes a spark coil having a primary connnected in series with the anode-cathode path of said thyristor, said series-connected primary and anode-cathode path being connected in parallel with said ignition capacitor, and wherein said voltageoperated switch means is connnected to the control electrode of said thyristor.

26. An ignition arrangement as defined in claim 24, wherein said electronic switch means includes a thyristor rendered conductive by said control signal, and resistor means in series with said thyristor, said thyristor and resistor means being connected in parallel across said ignition capacitor, and wherein said voltage-operated switch means is connected to the control electrode of said thyristor.

meme

27. An ignition arrangement as defined in claim 25, wherein said series-connected capacitor and resistor are connected in parallel with said ignition capacitor, the capacitor end and the resistor end being respectively connected to the positive and negative plates of said ignition capacitor.

28. An ignition arrangement as defined in claim 26, wherein said series-connected capacitor and resistor are connected in parallel with said ignition capacitor, the capacitor end and the resistor end being respectively connected to the positive and negative plates of said ignition capacitor.

29. An ignition arrangement as defined in claim 8, wherein said electronic switch means includes a thyristor rendered conductive by said control signal, and resistor means in series with said thyristor, said thyristor and resistor means being connected in parallel with said ignition capacitor, and further including a series-connected capacitor end resistor of which the capacitor end and the resistor end are connected to respective ends of said control signal winding; normally non-conductive voltage-operated switch means connected to the junction between said series-connected capacitor and resistor and to the control electrode of said thyristor for rendering the latter conductive when the engine speed exceeds a predetermined value, said voltage-operated switch means becoming conductive when the voltage at said junction exceeds a predetermined value, and the cathode of said thyristor being connected to said resistor end of said series-connected capacitor and resistor.

30. An ignition arrangement as defined in claim 8, including a series-connected capacitor and resistor; a diode connecting the junction between said series-connected capacitor and resistor to one end of said control signal winding to conduct only positive signals, the other end of the control signal winding being connected to the capacitor end of said series-connected capacitor and resistor; and normally non-conductive voltage-operated switch means connected between the resistor end of said connected capacitor and resistor and said electronic switch means for rendering the latter conductive when the engine speed exceeds a predetermined value, said voltage-operated switch means becoming conductive when the voltage across said capacitor exceeds a predetermined value.

31. An ignition arrangement as defined in claim 30, wherein said electronic switch means includes a thyristor rendered conductive by said control signal, and said winding means includes a spark coil having a primary connected in series with the anode-cathode path of said thyristor, said series-connected primary and anode-cathode path being connected in parallel with said ignition capacitor, and wherein the capacitor end of said series-connected capacitor and resistor is connected to the cathode of said thyristor, and said voltage-operated switch means connects the resistor end of said series-connected capacitor and resistor to the control electrode of said thyristor.

32. An ignition arrangement as defined in claim 30, wherein said electronic switch means includes a thyristor rendered conductive by said control signal, and resistor means in series with said thyristor, said thyristor and resistor means being connected in parallel with said ignition capacitor, and wherein the capacitor end of said series-connected capacitor and resistor is connected to the cathode of said thyristor, and said voltage-operated switch means connects the resistor end of said series-connected capacitor and resistor to the control electrode of said thyristor.

33. An ignition arrangement as defined in claim 11, including load resistor means connected across said control signal winding.

34. An ignition arrangement as defined in claim 33, including normally non-conductive voltage-operated switch means connected between one terminal of said load resistor means and said electronic switch means for rendering the latter conductive when the engine speed exceeds a predetermined value, said voltageoperated switch means becoming conductive when the voltage across said load resistor means exceeds a predetermined value.

35. An ignition arrangement as defined in claim 29, wherein said electronic switch means includes a thyristor rendered conductive by said control signal, and said winding means includes a spark coil having a primary connected in series with the anode-cathode path of said thyristor, said series-connected primary and anode-cathode path being connected in parallel with said ignition capacitor, and wherein said voltageoperated switch means is connected to the control elec trode of said thyristor, and the cathode of said thyristor is connected to the other terminal of said load resistor.

36. An ignition arrangement as defined in claim 34, wherein said electronic switch means includes a thyristor rendered conductive by said control signal, and resistor means in series with said thyristor, said thyristor and resistor means being connected in parallel with said ignition capacitor, and wherein said voltageoperated switch means is connected to the control electrode of said thyristor, and the cathode of said thyristor is connected to the other terminal of said load resistor.

Claims

1. In an internal combustion engine, a speed-limiting ignition arrangement comprising at least one spark plug; an ignition capacitor; first means for generating charging signals and ignition signals timed in synchronism with the rotation of said engine, and including means for generating a control signal preceding the respective signal when the speed of said engine exceeds a predetermined value; discharge means for effecting firing of said spark plug upon receipt of an ignition signal by permitting transmission to said spark plug of energy stored in said capacitor, and including additional means operative upon receipt of said control signal for preventing said capacitor from being in charged condition during generation of the respective subsequent ignition signal.

9. An ignition arrangement as defined in claim 3, wherein said winding means includes a control signal winding in which said control signal is induced by said magnet means, and further including a stationary control signal magnetic core for said control signal winding, and core means for the rest of said winding means.

14. An arrangement as defined in claim 1, wherein said discharge means and additional means together comprise a single discharge path including electronic switch means responsive to both said ignition and control signals.

15. An ignition arrangement as defined in claim 3, wherein said electronic switch means includes a thyristor rendered conductive by said control signal and said winding means includes a spark coil having a primary connected in series with the anode-cathode path of said thyristor, said series-connected primary and anode-cathode path being connected in parallel with said ignition capacitor.

24. An ignition arrangement as defined in claim 21, including normally non-coNductive voltage-operated switch means connected to the junction between said series-connected capacitor and resistor and to said electronic switch means for rendering the latter conductive when the engine speed exceeds a predetermined value, said voltage-operated switch means becoming conductive when the voltage at the junction exceeds a predetermined value.

25. An ignition arrangement as defined in claim 24, wherein said electronic switch means includes a thyristor rendered conductive by said control signal, and said winding means includes a spark coil having a primary connnected in series with the anode-cathode path of said thyristor, said series-connected primary and anode-cathode path being connected in parallel with said ignition capacitor, and wherein said voltage-operated switch means is connnected to the control electrode of said thyristor.

34. An ignition arrangement as defined in claim 33, including normally non-conductive voltage-operated switch means connected between one terminal of said load resistor means and said electronic switch means for rendering the latter conductive when the engine speed exceeds a predetermined value, said voltage-operated switch means becoming conductive when the voltage across said load resistor means exceeds a predetermined value.

35. An ignition arrangement as defined in claim 29, wherein said electronic switch means includes a thyristor rendered conductive by said control signal, and said winding means includes a spark coil having a primary connected in series with the anode-cathode path of said thyristor, said series-connected primary and anode-cathode path being connected in parallel with said ignition capacitor, and wherein said voltage-operated switch means is connected to the control electrode of said thyristor, and the cathode of said thyristor is connected to the other terminal of said load resistor.

36. An ignition arrangement as defined in claim 34, wherein said electronic switch means includes a thyristor rendered conductive by said control signal, and resistor means in series with said thyristor, said thyristor and resistor means being connected in parallel with said ignition capacitor, and wherein said voltage-operated switch means is connected to the control electrode of said thyristor, and the cathode of said thyristor is connected to the other terminal of said load resistor.