US3598098A

US3598098A - Ignition arrangment for internal combustion engines

Info

Publication number: US3598098A
Application number: US821034A
Authority: US
Inventors: Gerhard Sohner; Gert Strelow; Bernd Bodig
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1968-05-02
Filing date: 1969-05-01
Publication date: 1971-08-10
Anticipated expiration: 1988-08-10
Also published as: GB1265062A; DE1807541B2; ES366698A1; SE367098B; SE367098C; FR2009850A1; DE1807541A1

Abstract

An ignition arrangement for internal combustion engines in which a magnetic core member has one pole for carrying the charging winding and another pole for carrying a control winding. The charging winding serves to charge a capacitor which stores the ignition energy for firing the spark plug of the engine. A magnet mounted on a rotatable disc is moved past the poles of the core member and thereby induces voltages, in sequence, within the charging and control windings. The capacitor discharges through the primary winding of an ignition transformer, with the discharge controlled by a control rectifier. The control electrode of the rectifier is connected to the control winding of the magnetic core member. Upon discharge of the capacitor, an ignition pulse for firing the spark plugs is induced in the secondary winding of the ignition transformer.

Description

United States Patent [54] IGNITION ARRANGMENT FOR INTERNAL COMBUSTION ENGINES l2 Claims,4 Drawing Figs.

[52] U.S.Cl 123/148 E, 123/41 E, 123/1465 A, 123/149 D [51] lnt. F02p 3/06 [50] FieldolSeareh 123/1465, 148 E, 149, 149 D, 148 AC,41E',310I10,153; 315/209 [56] References Cited UNITED STATES PATENTS 3,447,521 6/1969 Piteo 123/148 3,484,677 12/1969 Piteo 123/148 X Primary Examiner-Laurence M. Goodridge Attorney-Michael S. Striker ABSTRACT: An ignition arrangement for internal combustion engines in which a magnetic core member has one pole for carrying the charging winding and another pole for carrying a control winding. The charging winding serves to charge a capacitor which stores the ignition energy for firing the spark plug of the engine. A magnet mounted on a rotatable disc is moved past the poles of the core member and thereby induces voltages, in sequence, within the charging and control windings. The capacitor discharges through the primary winding of an ignition transformer, with the discharge controlled by a control rectifier. The control electrode of the rectifier is connected to the control winding of the magnetic core member. Upon discharge of the capacitor, an ignition pulse for firing the spark plugs is induced in the secondary winding of the ignition transformer.

IGNITION ARRANGMENT FOR INTERNAL COMBUSTION ENGINES I BACKGROUND OF THE INV ENTION The present invention resides in an ignition arrangement for internal combustion engines in which an ignition capacitor serves to store the ignition energy. The capacitor is charged through a charging coil which has a voltage induced within it. The capacitor is discharged with the aid of a contactless controlled electronic switch, through the primary winding of an ignition transformer. The secondary winding of this transformer is connected to at least one spark plug.

Such ignition arrangements are particularly adapted to operate in cases where a battery is not available as an energy source for supplying power or feeding the ignition arrange ment. Furthermore, no mechanical switches with their accom panying disturbances or noise effects are required. A particular simple arrangement may be realized, in accordance with the present invention, which also guards against operation of the ignition arrangement in the wrong or incorrect rotational direction. In accordance with the present invention, a ferromagnetic core is provided in which one pole forms the charging armature by carrying a charging winding, and a second pole forms the control armature by carrying a control winding. Charging and control voltages are induced within these windings through a magnet which is driven by the internal combustion engine and is moved past the charging armature and the control armature.

SUMMARY OF THE INVENTION An ignition arrangement for internal combustion engines in which a ferromagnetic core is designed with a first pole carrying a charging winding, and a second pole carrying a control winding. A magnet is mounted upon a rotatable member driven from the crank shaft of the engine. When the poles of the magnet on the rotatable member are driven past the poles of the ferromagnetic core carrying the charging and control windings, voltages are induced respectively within these windings. An air gap is maintained between the pole carrying the control winding and the remainder of the ferromagnetic core, for the purpose of magnetically isolating the pole with the control winding from the core proper. The voltage induced within the charging winding charges a capacitor which stores the ignition energy. The capacitor becomes discharged through a control rectifier which discharges the energy from the capacitor through the primary winding of an ignition transformer, when actuated by the control voltage induced within the control winding. With the discharge of the ignition capacitor in this manner, an ignition voltage pulse is induced within the secondary winding of the ignition transformer which is connected to one or more spark plugs. A safety means is provided whereby firing of the spark plug is prevented when the rotatable member rotates in the wrong direction.

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 DRAWINGS FIG. 1 is a functional and electrical circuit diagram and FIG. 3 is a graphical representation of the induced voltages in the charging winding and control winding on the ferromagnetic core of FIG. 1, when the rotatable member used for inducing these voltages rotates in the wrong direction; and

FIG. 4 is a further embodiment of the ignition arrangement, in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawing and in particular to FIG. I, the ferromagnetic core I0 is designed in the form of three sections or members. The first pole II carries a charging coil 12 on a charging armature. A second pole 13 designated as a control armature has wound upon it a control coil or winding 14. The middle or third pole I5 carries the primary winding 16 and the secondary winding I7 of an ignition transformer. An air gap 28 between the pole I3 and the remaining portion of the ferromagnetic core 10 is provided for the purpose of magnetically decoupling the control armature designated as the third pole 13 from the remaining ferromagnetic core. In the vicinity or proximity of the ferromagnetic core 10, a disc 18 is rotatably mounted. The disc is driven through a coupling represented by the dash-dot lines to the internal combustion engine, not shown. A magnet 19 is mounted at the external rim of the disc I8, so that the

magnetic poles

20 and 21 of this magnet 19 are moved past the poles I1, I3 and I5 of the ferromagnetic core I0. This magnet I9 is arranged on the disc I8 so that the poles of this magnet move closely past these poles 11, I3 and I5 as the disc is rotated.

On end or terminal of the control winding 14 on the pole I3 is connected to ground potential, whereas the other end or terminal of this control winding 14 is connected to the anode or a diode 22. The cathode of this diode 22 is connected, in turn, to the control electrode of a thyristor 23. The cathode of this thyristor 23 has ground potential applied to it, whereas the anode is connected to one end or terminal of the primary winding 16 of the ignition transformer. The junction of the primary winding 16 with the secondary winding I7 of the ignition transfon'ner is connected to an ignition capacitor 24 and to the cathode of a charging rectifier 25. The anode of this charging rectifier or diode 25 leads to ground potential through the charging winding or coil I2. The other electrode of the capacitor 24 is also connected to ground potential. A spark plug 26 is connected, with one terminal, to the secondary winding I6, whereas the other terminal of this spark plug has ground potential applied to it.

In operation of the ignition arrangement, the correct rotational direction for the disc 18 is shown in FIG. 2. With this rotational direction of the disc 18, a voltage is induced in the charging coil 12 of the charging armature designated with the pole I]. A voltage is also then induced within the control winding 14. The induced voltages result from the motion of the

poles

20 and 21 of the magnet 19 past the poles II and 13. Thus, these voltages are induced through the cutting action of the magnetic field of the magnet I9, produced as the latter moves past the poles II and 13, in sequence. The voltage induced within the coil 12 is initiated when the disc 18 is in the position a. The function of the induced voltage withinv the charging coil 12 and the control I4 is designated in broken lines in FIG. 2. This voltage is of no consequence for charging the ignition capacitor. There is, however, the dangerous possibility that this half-wave fires the thyristor and thereby prevent charging of the capacitor 24. For this reason, a ferromagnetic member 27 is joined to the first pole II for the purpose of weakening the effect of the flux variation incurred when the

magnetic poles

20 and 21 move past the pole II. The ferromagnetic member 27 provides that the undesired or disturbing voltage is suppressed to a substantially small residue, so that the function designated with solid lines in FIG. 2 is realized.

In the position b of the disc 18, the variation of the magnetic flux linking the charging coil 12, is maximum. As a result, the induced charging voltage U achieves, in this position of the disc 18, a maximum value or level. The charging voltage U is induced within the charging coil 12 as a result in the variation in the magnetic flux. Due to the charging voltage U the ignition capacitor 24 becomes charged through the charging diode or rectifier 25. When the disc 18 is in the position between locations and d, a predetermined control voltage U is induced, and the thyristor 23 becomes fired at the firing or ignition instant 2?, when the induced control voltage has reached a predetermined level. The capacitor 24 then discharges through the primary winding 16 of the ignition transformer. The high voltage induced, thereby, within the secondary winding 17, produces a spark to cross the gap of the spark plug 26.

The ignition arrangement of the present invention exhibits the particular advantage that when the disc 18 rotates in the wrong direction, the ignition arrangement does not provide sufficient ignition voltage. As a result, reverse operation of the engine is inhibited. This process is particularly clearly shown in FIG. 3.

When the disc 18 rotates in the wrong direction, the polarity of the charging voltage U ,and the control voltage U is reversed. The capacitor 24 would, thereby, become essentially charged through the half-wave produced when the disc 18 is in the position c. Such charging of the capacitor can, however, not take place, since the thyristor 23 is maintained in the conducting state, at that instant, through the control voltage U The low charging voltage with which the ignition capacitor 24 becomes charged when the disc in the position a, is at such a low level due to the presence of the ferromagnetic member 27, so that a spark cannot appear across the electrodes of the spark plug 26.

The half-cycle of voltage produced at a is largely caused by the magnetic leakage flux present at this position. This voltage could cause so great a charge on capacitor 24 that the spark plug could produce a hot spark, despite the overlapping of the charging and control voltages at position c. The member 27 partly short circuits the leakage flux and therefore causes a lower induced voltage, as shown in full line in FIG. 3. This lower voltage is too small to cause a hot spark.

A further advantage of the ignition arrangement, in accordance with the present invention, resides in the feature that the leading pulse edges of the control voltage become steeper when the rotational speed of the engine and hence the disc 18 increases, provided that the engine is rotating in the correct direction. As a result of this condition, the switching threshold of the thyristor is realized more rapidly between the positions c and d/This feature or process has the effect of advancing the ignition instant and thereby increase the power output of the internal combustion engine.

The ferromagnetic core is designed, in the preceding embodiment, in the form of a three-pole core having a middle pole which carries the ignition transformer. This ferromagnetic core 10 can also be designed in the form of a core with two poles in which the ignition transformer is arranged or mounted in any desired position.

In the event that it is of advantage from the viewpoint of space conservation, the control armature can also be mounted within a disc coupled to the internal combustion engine. in such an arrangement, the disc includes or contains a second permanent magnet with interior poles.

A particularly advantageous design and fabrication of the ignition arrangement has been found from the viewpoint of low cost and simplicity, when the pole carrying the control winding exhibits lower strength than the pole carrying the charging winding.

in another embodiment, in accordance with Fit). 4, the windings upon the ferromagnetic core 10 are interchanged in their series connection. The three-member ferromagnetic core 10 carries upon its first pole II, the primary winding 16, as well as the secondary winding 17 of the ignition trans former. The charging coil 12 is wound upon the second pole l5, and the control armature designated as the third pole 13, carries the control winding 14. For the purpose of decoupling magnetically the pole 13 from the remaining ferromagnetic core, an air gap 28 is provided between the pole l3 and the remaining portion of the ferromagnetic core 10, similar to that described in relation to the first embodiment. Since the necessary control voltage can also be considerably small in this embodiment, the pole for the control armature will suffice with less strength than the remaining ferromagnetic core 10. The control armature can, in particular, be formed of individual laminations. Through such construction, particular fabrication advantages and fabrication economies are realized. The disc 18 is rotatably mounted in the proximity of the ferromagnetic core 10. The disc is driven by the internal combustion engine through a coupling shaft designated in the drawing through a dash-dot line. The magnet 19 is arranged along the outer rim of the disc 18, and the poles 20 and 2! of the magnet 19 pass closely the poles of the ferromagnetic core 10 in the rotation of the disc. The functional operation of this particular embodiment is basically identical to that described in relation to the preceding embodiment. For the purpose of securing the safety feature against return motion over the entire rotational region, the second embodiment has, however, the ferromagnetic member 27 on the third pole instead of the first pole viewed from the direction of motion.

The purpose of the member 27 is to suppress undesired voltage pulses, arising from leakage flux, that could cause the spark plug to spark when it should not.

An additional advantage is realized through this arrange ment of the ferromagnetic core 10 in which the wound coils follow in series, in the direction of motion, with the sequence of the

ignition transformer

16 and 17, the charging coil 12, and the control winding 14, in contrast to the first embodiment. This advantage results from the condition that the maximum magnetic flux appearing at the center pole ll may be used for charging the ignition capacitor. Through this feature, a relatively large charge may be achieved with a low number of turns in the charging winding.

The ignition arrangement as described above in relation to one spark plug, can also be used in conjunction with installations or arrangements using a number or plurality of spark plugs. When using a larger number of such spark plugs, the ignition voltage pulse may be applied to the spark plugs through an ignition distributor, as known in the art, and the rotational speed of the disc i8 may, for example, be increased.

it is also possible, furthermore, to hold the disc 18 stationary and to rotate the ferromagnetic core 10 instead.

The thyristor used in the embodiment, as described, can also be replaced through another electronic switch which consists of, for example, electronic vacuum tubes or semiconductor elements in the form of transistors or diodes.

For particular applications, the electrical circuit and/or the wound ferromagnetic core may be embedded within a plastic mass board around them in a process known in the art as potting. in a particular advantageous design, the electronic components of the circuit are mounted on a hard fiber board secured to the ferromagnetic core 10.

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 construction differing from the types described above.

While the invention has been illustrated and described as embodied in an ignition arrangement 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.

What we claim 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, a magnetic core member with first and second spaced poles; a charging winding carried by said first pole; a control winding carried by said second pole; magnetic means linked drivenly to said internal combustion engine and driven past said first and said second poles in turn,

winding; transformer means having primary and secondary windings; electronic switching means controlled by said control voltage induced in said control winding for discharging said capacitor means through said primary winding of said transformer means, said magnetic means and charging and control windings being arranged so that said charging voltage induced in said charging winding occurs before said control voltage induced in said control winding when the engine rotates in the desired direction and so that said charging and control voltage overlap when the engine rotates in opposite direction, whereby an ignition causing pulse for at least one spark plug is induced in said secondary winding only w ten the engine rotates in said desired direction.

2. The ignition arrangement as defined in claim 1, wherein said magnetic core member includes a third pole.

3. The ignition arrangement as defined in claim 2, including a rotatable disc for supporting said magnetic means, said transformer means being mounted on said third pole, so that in the desired direction of rotation of the engine said magnetic means moves past said first pole, said second pole next, and finally said third pole.

4. The ignition arrangement as defined in claim l, wherein said magnetic core member includes an auxiliary pole for carrying said transformer means, and further including rotatable disc means, rotated by the engine, for supporting said magnetic means, said magnetic means, when the engine rotates in the desired direction, successively moving past the pole carrying said transformer means, the pole carrying said charging winding, and the pole carrying said control winding.

S. The ignition arrangement as defined in claim 1 including armature means spaced from said magnetic core member for carrying said transformer means.

6. The ignition arrangement as defined in claim 1 wherein said second pole carrying said control winding is spaced from the remaining portion of said magnetic core member through an air gap.

7. The ignition arrangement as defined in claim I wherein the pole carrying said control winding has a lower amount of magnetic flux than the pole carrying said charging winding.

8. The ignition arrangement as defined in claim 1 wherein said pole carrying said control winding is comprised of individual laminations.

9. The ignition arrangement as defined in claim 1 including hard fiber board means carried by said magnetic core member and said capacitor means, transformer means and electronic switching means being arranged on said hard fiber board means.

10. The ignition arrangement as defined in claim I including plastic means for embedding said magnetic core member, said capacitor means, said transformer means and electronic switching means.

'1 l. The ignition arrangement as defined in claim 1 including ferromagnetic means upon said pole carrying said charging winding for reducing the amplitude of undesired pulses induced in said charging winding.

12. The ignition arrangement as defined in claim 4 including ferromagnetic means on said pole carrying said control winding for suppressing undesired voltage pulses arising from leakage flux that could cause unintentional sparking of the spark plug.

Claims

1. An ignition arrangement for internal combustion engines comprising, in combination, a magnetic core member with first and second spaced poles; a charging winding carried by said first pole; a control winding carried by said second pole; magnetic means linked drivenly to said internal combustion engine and driven past said first and said second poles in turn, whereby a charging voltage is induced in said charging winding and a control voltage is induced in said control winding; capacitor means for storing the ignition energy and adapted to be charged by said charging voltage induced in said charging winding; transformer means having primary and secondary windings; electronic switching means controlled by said control voltage induced in said control winding for discharging said capacitor means through said primary winding of said transformer means, said magnetic means and charging and control windings being arranged so that said charging voltage induced in said charging winding occurs before said control voltage induced in said control winding when the engine rotates in the desired direction and so that said charging and control voltages overlap when the engine rotates in opposite direction, whereby an ignition causing pulse for at least one spark plug is induced in said secondary winding only when the engine rotates in said desired direction.

4. The ignition arrangement as defined in claim 1, wherein said magnetic core member includes an auxiliary pole for carrying said transformer means, and further including rotatable disc means, rotated by the engine, for supporting said magnetic means, said magnetic means, when the engine rotates in the desired direction, successively moving past the pole carrying said transformer means, the pole carrying said charging winding, and the pole carrying said control winding.

5. The ignition arrangement as defined in claim 1 including armature means spaced frOm said magnetic core member for carrying said transformer means.

7. The ignition arrangement as defined in claim 1 wherein the pole carrying said control winding has a lower amount of magnetic flux than the pole carrying said charging winding.

10. The ignition arrangement as defined in claim 1 including plastic means for embedding said magnetic core member, said capacitor means, said transformer means and electronic switching means.

11. The ignition arrangement as defined in claim 1 including ferromagnetic means upon said pole carrying said charging winding for reducing the amplitude of undesired pulses induced in said charging winding.