US3648675A

US3648675A - Ignition arrangements for internal combustion engines

Info

Publication number: US3648675A
Application number: US55080A
Authority: US
Inventors: Georg Gemander
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1969-07-16
Filing date: 1970-07-15
Publication date: 1972-03-14
Anticipated expiration: 1989-03-14
Also published as: DE1936105B2; FR2052681A5; ES381813A1; DE1936105A1; YU33675B; YU159770A; AT305702B; SE355213B; JPS4826683B1

Abstract

An arrangement for providing ignition pulses for an internal combustion engine while at the same time inhibiting ignition pulses from being applied when said engine is operated in the improper direction. Ignition pulses are produced through an ignition coil which has its primary winding connected to a capacitor charged through a magneto generator. Discharging of the capacitor is controlled through a thyristor which, in turn, is fired through the application of pulses derived from pulse emitters. The thyristor is switched to the conducting state, during improper operating direction of the engine, by the voltage pulse which causes charging of the capacitor when the thyristor is in the nonconducting state.

Description

United States Patent Gemander air. 1, 1972 [54] IGNITION ARRANGEMENTS FOR 3,566,188 2/1971 Minlcs ..123/148 E X MNTIERNAL COMBUSTION ENGINES 3,435,264 3/1969 Brand et a1. ..123/148 E X [72] Inventor: Georg Gemander, Nurnberg, Germany primary Examiner Laul-ence M goodridge [73] Assignee: Robert Bosch Gmblii, Stuttgart, Germany A"mey M1chael smker [22] Filed: July 15, 1970 [57] STRACT [21] Appl. No.: 55,080 An arrangement for providing ignition pulses for an internal combustion engine while at the same time inhibiting ignition pulses from being applied when said engine is operated in the [30] Forelgn Apphcauon Emmy Dam improper direction. Ignition pulses are produced through an July 16, 1969 Germany ..P 19 36 105.8 ignition coil which has its primary winding connected to a capacitor charged through a magneto generator. Discharging [52] U.S.Cl ..123/149 A, 123/41, 123/ 146.5 A, of the capacitor is controlled through a thyristor which, in 123/149 C, 123/149 D turn, is fired through the application of pulses derived from [51] llnt.Cl ..F02p 1/00 pulse emitters. The thyristor is switched to the conducting [58] Field of Search ..123/ 148 E, 149 A, 149 D, 41, state, during improper operating direction of the engine, by 123/ 146.5 A; 315/209 the voltage pulse which causes charging of the capacitor when the thyristor is in the nonconducting state. [56] Reterences Cited 11th C in 8 Drill lFigurm UNITED STATES PATENTS Burson ..123/148 E X Patented March 14, 1912 3,648,675

2 Sheets-Sheet l IN VE NTOR Geor g GEMANDER l-ll a [fl-l his ATTORNEY Patented March 14, 1972 2 Sheets-Sheet 2 I Fig.4c

his ATTORNEY IGNITION ARRANGEMENTS FOR INTERNAL COMBUSTION ENGINES BACKGROUND OF THE INVENTION The present invention resides in an ignition arrangement for internal combustion engines in which a capacitor becomes charged from a magneto generator, and then becomes discharged at the instant of ignition through the primary winding of an ignition coil, upon actuation of an electronic circuit. The secondary winding of the ignition coil is connected to the spark plug of the engine.

It is known in the art to provide a thyristor in such electronically controlled capacitor type of ignition arrangements, and to fire the thyristor at the instant of ignition through a voltage pulse. The voltage pulse for firing the thyristor is generated through a magnetic type of generator or emitter which operates in conjunction with a moving element that passes or conducts flux lines. As soon as this element which passes or conducts flux lines, moves beneath the pole pieces of the pulse emitters or generators, in operation of the engine, the magnetic circuit of the pulse generator becomes briefly closed. As a result of the closure, and the change of the magnetic flux within the induction coil of the generator, thereby, a positive voltage pulse with a subsequently following negative pulse become induced. Whereas the positive pulse is used for ignition purposes, the negative pulses are blocked through a diode, and thereby remain ineffective. Such ignition arrangements have, however, the disadvantage that when operating in reverse as, for example, at the start, the previous negative pulse derived from the pulse generator, becomes a positive pulse due to the changed direction of motion. The resulting positive pulse causes the thyristor to be switched to the conducting state, and accordingly the capacitor becomes discharged through the ignition coil and a spark is thereby applied at the spark plug. With such operation of the spark plug, the engine is aided in running in the wrong direction.

Accordingly, it is an object of the present invention for providing, in an ignition combustion engine, means for inhibiting the generation of sparks or sparking of the plugs within the engine, when the latter operates in the reverse direction. It is particularly an object of the present invention to provide such an arrangement for engines having one or more cylinders.

The objects of the present invention are achieved by providing for switching the thyristor to the conducting state, as soon as the half wave of a voltage is produced during the wrong direction of motion of the magneto generator. Such halfwave would, otherwise, cause charging of the capacitor which is connected to the magneto generator, should the electronic switching element in the form of the thyristor be turned off. The switching of the thyristor, thereby, takes place in the simplest manner when the engine operates in the wrong direction, and such switching of the thyristor is accomplished by the voltage pulse of a magnetic generator or pulse emitter which switches the thyristor to the conducting state. When the engine is operated in the proper direction, the pulse emitter provides the pulse for switching the thyristor to the conducting state at the instant of ignition.

SUMMARY OF THE INVENTION An ignition arrangement for internal combustion engines in which a capacitor charged by a magneto generator discharges through the primary winding of an ignition coil upon firing of a thyristor. The anode-cathode path of the thyristor is connected in series with the primary winding of the ignition coil. The gate of the thyristor has a voltage pulse applied to it through a pulse emitter. The thyristor is switched to the conducting state upon generation of a voltage pulse which would charge the capacitor through the magneto generator, at the instunt of ignition, and when the thyristor is in the non-conducting state. When the engine is operating in the improper direction, the thyristor is switched to the conducting state and inhibits, thereby, the charging of the capacitor.

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 ob jects 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 functional schematic diagram of an internal combustion engine with two cylinders and a magneto generator for charging an ignition capacitor, in accordance with the present invention;

FIG. 2 is a circuit diagram of the arrangement of FIG. 1;

FIGS. 3a, 3b and 3c are voltage waveforms of the armature winding induced pulses of the ignition generator arrangement when operated in the proper direction of motion; and

FIGS. 4a, 4b and 4c are voltage waveforms prevailing in the ignition arrangement when the engine is operated in the improper direction.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawing, and in particular to FIG. I, an internal combustion engine with two cylinders and of two cycle design, is provided with a magneto generator ltll. This generator consists of a pole wheel 131 provided with four symmetrically arranged permanent magnets 12. These permanent magnets 12 are arranged so that they are situated with alternating polarity. The generator, furthermore, has an armature plate 13 upon which are mounted a charging armature M for producing the ignition energy, and ignition capacitor I5 for storing the ignition energy, a well as two oppositely lying magnetic pulse emitters l6 and 17. The elements mounted upon the armature 13, are connected to a circuit 22 situated outside of the generator 10, through interconnecting

lines

18,19,20 and 21. Two

ignition coils

23 and 24, are, furthermore, connected to the ignition circuit 22. The high voltage portions of these ignition coils have

terminal lines

25 and 26 connected to both

spark plugs

27 and 28 which are arranged in the combustion chamber of the engine.

The functional operation of the ignition arrangement may be obtained from FIGS. 2, 3 and 4. FIG. 2 shows precisely the circuit construction of the ignition arrangement shown in FIG. 1. With normal rotation in the normal direction, an alternating voltage U is generated within the charging armature M of the generator 10, through the rotating pole: wheel II. This voltage U is shown in FIG. 3a. The next positive halfwave which appears as a result of the electrical energy produced in the magnetic generator 10, is applied to the ignition capacitor 15, through a diode 30. As a result, the ignition capacitor 15 becomes charged. Since the diode 3t] prevents discharging of the ignition capacitor 15 through the charging armature 14, the capacitor voltage U appears as shown in FIG. 3c. In this latter diagram, the capacitor voltage has a maximum value for the positive voltage halfwave of substantially volts.

With further rotation, the element 29 which is connected to the motor shaft and which serves to pass the flux lines, is moved beneath the magnetic generator 16 at the instant at which the negative halfwave within the charging armature M has attained its maximum value. Through the element 29, variation in the magnetic flux takes place within the generator 16. As shown in FIG. 3b, first a positive and then a negatively following voltage pulse U of approximately 1.8 volts is induced. The positive voltage pulse is applied to the control gate of a thyristor 32, through a diode 31. With the application of this positive voltage pulse to this thyristor, the latter is switched to the conducting state. The ignition capacitor 15 becomes thereby suddenly discharged, as shown in FIG. 3c, since the circuit through the primary winding 23a of the ignition coil 23 and the thyristor 32, is close to ground. As a result, an ignition voltage is induced within the secondary winding 23b of the ignition coil 23. This ignition voltage is then applied to the spark plug 27 for the purpose of producing a spark across the electrodes of the plug.

With further rotation of the magnetic pole wheel 11, a I

second positive halfwave voltage is induced within the charging armature or charging coil 14, and this voltage halfwave serves to charge again the ignition capacitor through the diode 30. Since the two magnetic generators l6 and 17 lie opposite to each other as shown in FIG. 1, the element 29 is moved beneath the second generator 17 with further rotation of l80. As a result, a positive and subsequently following negative voltage pulse are also here generated. The positive voltage pulse is applied to the control gate of a second thyristor 34 through a further diode 33, and switches the thyristor, thereby, to the conducting state. In this manner, the ignition capacitor 15 becomes discharged through the primary winding 24a of the second ignition coil 24, and through the thyristor 34. In this manner, a high voltage results also in the secondary winding 24b of the ignition coil 24, and this high voltage is applied to the spark plug 28 for producing a further spark. The negative voltage pulse appearing at both

magnetic generators

16 and 17 have no effect upon the associated thyristors 32 and 34, since the

diodes

31 and 33 will not conduct. To protect the thyristors 32 and 34 against excess voltages, the control gates are connected to ground potential through a resistor 35 and a capacitor 36 connected in parallel therewith.

When the internal combustion engine is operated in the wrong rotational direction, the voltage halfwaves induced within the charging coil or armature 14 have the reversed sequence and reverse direction. The last negative halfwave shown in FIG. 3a, becomes thereby the first positive halfwave, as shown in broken lines in FIG. 4a, during incorrect rotational direction. This also applies to the voltage pulses of the magnetic generator 17 whose negative pulses now become positive ones, as shown in FIG. 4b. These positive pulses are applied to the control gate of the thyristor 34 and switch the latter to the conducting state at the instant that the positive halfwave at the charging coil 14 begins. The circuit through the charging coil 14, diode 30, as well as through the primary winding 24a of the ignition coil 24, becomes closed. As a result, the charging of the ignition capacitor 15 is prevented.

Since the primary winding 24a of the ignition coil 24 has 'a relatively low resistance value, the actual voltage at the charging armature or charging coil 14 is very small, and consequently the voltage at the ignition capacitor 15 is also small. This may be seen from the extended line in FIGS. 4a and 4c. Through such action, therefore, no spark appears at the spark plug 28.

Since the thyristor 34 remains in the conducting state as long as current flows in the circuit, the thyristor becomes turned off first after the end of the positive halfwave from the charging armature or coil 14. With further rotation of the pole wheel 11, a negative halfwave becomes now induced within the charging armature or coil 14, and this negative halfwave remains ineffective for the ignition arrangement, because the diode 30 remains in the non-conducting state. First after the positive halfwave at the charging armature or coil 14, can the ignition capacitor 15 become charged through the diode 30. Since, however, at that instant of time the element 29 becomes moved beneath the other generator 16, and a positive and negative voltage pulse becomes generated therein, the thyristor 32 becomes switched to the conducting state through the diode 31. As a result, the same procedure as before is repeated with respect to the thyristor 34. As shown in FIG. 4c, an insignificant voltage U appears at the capacitor 15 during the positive halfwave in the charging armature 14 upon resetting, but charging of the capacitor does not take place.

The cooperative arrangement of the

generator

16 and 17 with the element 29 is essential for assurance of proper resetting of the ignition arrangement. It is necessary to arrange the element 29 so that its rear end produces a positive pulse for the thyristors 32 and 34 at the instant of time when it is moved beneath the

magnetic generator

16 and 17, when the engine is rotated in the wrong direction. Through such conditions, a positive halfwave begins within the charging armature or coil 14, and charging of the ignition capacitor 15 is thereby avoided with safety.

The element 29, in an embodiment, extends preferably over an arc of 0.21 radians, or approximately 12. Accordingly, when the engine is rotated in the proper direction, the pulse produced with its front end within the

generator

16 or 17, appears within the region of the maximum value of the negative halfwave of the charging armature 14. This pulse determines the ignition instant and is used as the control pulse for the thyristors. Due to the narrow element 29, the magnetic circuit of the generator is directly closed and opened again in sequence. It has been found, thereby, that the positive and the negative generator pulse which follows directly, is larger than what would occur for a longer element 29, in which case the two generated pulses do not follow each other directly. The arrangement, therefore, also operates safely with small backup speeds.

The present invention is not limited for these particular embodiments illustrated. The present invention is, instead, applicable to single cylinder as well as multicylinder engines. in the latter case, the ignition arrangement is provided with a plurality of poles in the magneto generator, and a magnetic generator, furthermore, is provided for each thyristor control and cooperates with the rotating element 29, for example.

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 constructions differing from the types described above.

While the invention has been illustrated and described as embodied in ignition arrangements for internal 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.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by 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 meaning and range of equivalence of the following claims.

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

1. An ignition arrangement for internal combustion engines comprising, in combination, ignition coil means with primary and secondary windings for producing an ignition pulse in said secondary winding; charging capacitor means connected to said primary winding means for storing the ignition energy; connection means between said charging capacitor means and said primary winding means for discharging said ignition energy through said primary winding means; magneto generator means connected to said capacitor means for charging said capacitor means, said capacitor means discharging through said connection means and through said primary winding for producing said ignition pulse in said secondary winding; electronic switching means connected in series with said primary winding; means for connecting the series combination of said switching means and said primary winding in parallel with said capacitor means, said switching means and said primary winding being a conductive path across said capacitor means when said switching means is in the conducting state; pulse emitting means coupled to said engine and emitting pulses at spaced intervals; means for connecting said pulse emitting means to said switching means for controlling the state of said switching means, said switching means being switched to the conducting state by said pulse emitting means during a first operating direction of said engine whereby said capacitor means is inhibited from being charged by said generator means so that said ignition pulse is not produced in said secondary winding,

said switching means being switched to the non-conducting state when said engine is operating in a second direction whereby said capacitor means is charged by said generator means to produce said ignition pulse only when said engine is operating in said second direction.

2. The ignition arrangement as defined in claim ll, wherein said electronic switching means comprises thyristor means.

3. The ignition arrangement as defined in claim 1 including spark plug means connected to said secondary winding of said ignition coil means.

4. The ignition arrangement as defined in claim 2, wherein said pulses from said pulse emitting means switch said thyristor means to the conducting state at the instant of ignition when said engine operates in the second direction.

5. The ignition arrangement as defined in claim 4, wherein said pulse emitting means comprises electromagnetic means.

6. The ignition arrangement as defined in claim 1 including diode means connected to said capacitor means for charging said capacitor means with positive voltage from said magneto generator means, said electronic switching means being a thyristor switched to the conducting state through positive voltage pulses from said pulse emitting means.

7. The ignition arrangement as defined in claim 1, wherein said pulse emitting means comprises induction coil means; ferromagnetic means movable in proximity of said induction coil means so that a voltage is induced within said induction coil means for switching said electronic switching means to conducting state within substantially the maximum negative region of the voltage from said magneto generator means during said operating direction of said engine.

8. The ignition arrangement as defined in claim 7, wherein said ferromagnetic means comprises a substantially elongated ferromagnetic element extending over an arc of 0.21 radians.

9. The ignition arrangement as defined in claim 1, wherein said engine has a plurality of cylinders, each of said cylinders being associated with one electronic switching means and one pulse emitting means, all of said pulse emitting means being operated with one ferromagnetic element movable relative to said pulse emitting means.

10. The ignition arrangement as defined in claim 9, wherein said electronic switching means comprises a thyristor.

Claims

1. An ignition arrangement for internal combustion engines comprising, in combination, ignition coil means with primary and secondary windings for producing an ignition pulse in said secondary winding; charging capacitor means connected to said primary winding means for storing the ignition energy; connection means between said charging capacitor means and said primary winding means for discharging said ignition energy through said primary winding means; magneto generator means connected to said capacitor means for charging said capacitor means, said capacitor means discharging through said connection means and through said primary winding for producing said ignition pulse in said secondary winding; electronic switching means connected in series with said primary winding; means for connecting the series combination of said switching means and said primary winding in parallel with said capacitor means, said switching means and said primary winding being a conductive path across said capacitor means when said switching means is in the conducting state; pulse emitting means coupled to said engine and emitting pulses at spaced intervals; means for connecting said pulse emitting means to said switching means for controlling the state of said switching means, said switching means being switched to the conducting state by said pulse emitting means during a first operating direction of said engine whereby said capacitor means is inhibited from being charged by said generator means so that said ignition pulse is not produced in said secondary winding, said switching means being switched to the non-conducting state when said engine is operating in a second direction whereby said capacitor means is charged by said generator means to produce said ignition pulse only when said engine is operating in said second direction.

2. The ignition arrangement as defined in claim 1, wherein said electronic switching means comprises thyristor means.