US3915131A

US3915131A - Ignition system for internal combustion engines

Info

Publication number: US3915131A
Application number: US411522A
Authority: US
Inventors: Heinrich-Josef Brungsberg
Original assignee: BBC Brown Boveri France SA
Current assignee: BBC Brown Boveri AG Germany; BBC Brown Boveri France SA
Priority date: 1972-11-10
Filing date: 1973-10-31
Publication date: 1975-10-28
Anticipated expiration: 1992-10-28
Also published as: CH557471A; DE2255044A1; DE2255044B2; GB1409358A; IT999034B; FR2206797A5; JPS49100424A

Abstract

The ignition coil of an ignition system for internal combustion engines is provided with means for determining precisely the point of time of initiation of coil energization and with means for determining precisely the point of time of energy release, or coil de-energization. This is achieved by a disk rotating in synchronism with the internal combustion engine, markings on said disk and fixed sensor means for reading said markings as they are moved past said sensor means, and discriminator means having a predetermined threshold receiving the output of said sensor means and emitting signals whose timing is a function of the rpm at which said disk rotates past said sensor means.

Description

United States Patent Brungsberg 1 Oct. 28, 1975 IGNITION SYSTEM FOR INTERNAL 3,738,339 6/1973 Huntzinger et al. 123/117 R COMBUSTION ENGINES 3,756,212 9/1973 Schirmer et a1 123/148 E 3,799,136 3/1974 Korteling 123/148 E [75] Inventor: Heinrich-Josef Brungsberg,

Ludenscheid, Germany [73] Assignee: Brown, Boveri & Cie. A. G.,

Mannheim, Germany 9 [22] Filed: Oct. 31, 1973 [21] Appl. No.: 411,522

[30] Foreign Application Priority Data Nov. 10, 1972 Germany 2255044 [52] US. Cl. 123/117 R; 123/148 E [51] Int. C1. F02P 5/04 [58] Field of Search..... 123/117 R, 146.5 A, 148 E, 123/149 C [56] References Cited UNITED STATES PATENTS 2,852,590 9/1958 Fremon 1. 123/148 E 3,592,178 7/1971 Schiff 123/117 R 3,705,573 12/1972 Palazzetti et a1... 123/146.5 A 3,719,177 3/1973 Oishi et al 1231/1465 A Primary ExaminerCharles J. Myhre Assistant Examiner-Paul Devinsky Attorney, Agent, or Firm-Erwin Salzer [57] ABSTRACT The ignition coil of an ignition system for internal combustion enginesis provided with means for determining precisely t'he point of time of initiation of coil energization and with means for determining precisely the point of time of energy release, or coil deenergization. This is achieved. by a disk rotating in synchronism with the internal combustion engine, markings on said disk and fixed sensor means for reading said markings as they are moved past said sensor means, and discriminator means having a predetermined threshold receiving the output of said sensor means and emitting signals whose timing is a function of the rpm at which said disk rotates past said sensor means.

5 Claims, 5 Drawing Figures US. Patent Oct.28, 1975 Sheet10f5 3,915,131

1L. P818111 1 0a. 28, 1975 Sheet2 0f5 3,915,131

n (I/min) )joz()in 2ms 1 B()inO,22rns n NUMBER OF REVOLUTIONS PER MINUTE.

q: 0! =ANGLES ENCLOSED BETWEEN REFERENCE POINTS 1 AND 2 AND THE MARKINGS ON SIGNALLING DISK LILDIJY.

B =ANGLES ENCLOSED BETWEEN CONTIGUOUS MARKINGS ON SIGNALLING DISK LEDIE US. Pateht Oct. 28, 1975 Sheet4 of5 3,915,131

FIG,4

magnet-segment 0m. 28, 1975 Sheet 5 of5 3,915,131

U.S., Pam

train of waves train of waves pickup coil band pass filter IGNITION SYSTEM FOR INTERNAL COMBUSTION ENGINES BACKGROUND OF THE INVENTION This invention relates to ignition systems for internal combustion engines, and more particularly to means for determining the point of time at which storage of the energy required for ignition is to begin, and for determining the point of time at which the stored energy is to be released.

There are many different prior art ignition systems for internal combustion engines of which all are subject to serious drawbacks and limitations. Considering igni tion systems involving ignition coils whose current is interrupted periodically by separating interrupter contacts, since in such systems the aforementioned contacts must carry and must interrupt the entire current flowing through the ignition coil, this results in rapid and serious contact erosion. Such ignition systems are further subject to the drawback that their ignition coil must carry much larger currents when the number of revolutions of the internal combustion engine is small than required by the quantum of ignition energy to be released. When the number of revolutions of the internal combustion engine is relatively large, the amount of time available is not sufficient to store inductively the entire quantum of ignition energy required, so that the available ignition energy may be insufficient at relatively high numbers of revolution.

In order to reduce the current-carrying and currentinterrupting duty of the contacts of the interrupter, the current of the ignition coil may be controlled by semiconductor switching devices, so that the contacts of the interrupter have to carry and interrupt but the relatively small control current required by such switching devices. However, the other drawbacks of conventional ignition systems referred-to above are not eliminated by the use of semiconductor switching devices for controlling the current which flows through the ignition coil.

In capacitor ignition systems the energy required for ignition is initially stored inductively in an intermediate storage means, and transferred immediately thereafter to an ignition capacitor. There the energy required for ignition is stored virtually without any loss, until needed and released. One particularly desirable feature of such ignition systems resides in the fact that the current supplied to the inductive intermediate storage means may be limited to the extent dictated by ignition energy requirements. In other words, since inductive intermediate storage means do not require a holding current as conventional ignition coils do, and since at small numbers of revolution that current is a significant portion of the total current carried by conventional ignition coils, capacitor ignition systems are a considerable improvement over conventional ignition coil ignition systems. Capacitor ignition systems are, however, subject to a serious drawback consisting in that the du ration of the igniting sparks thereof is very short, and in some instances too short to effect ignition of the combustible air and gas mixture.

It has not been possible, heretofore, to provide eco nomically feasible ignition systems combining the desirable feature of capacitor ignition systems, i.e. low energy consumption, and the desirable feature of conventional ignition coil systems, i.e. sufficient duration of the spark discharge. It is, therefore, the primary object of the present invention to provide ignition systems for internal combustion engines which combine the desirable features of the two above referred-to prior art ignition systems. Other objects of this invention will become apparent as this specification progresses.

If onewishes to store in an ignition coil a predetermined quantum of ignition energy, this calls for a predetermined period of time following closing of circuit of the coil. The aforementioned predetermined period of time depends upon the inductance of the coil. If the required quantum of energy is stored, but not yet needed at the pointof time storage is completed, the flow of current must continue. This continued flow of current is referred-to as holding current. The holding current is eliminated if the circuit of the ignition coil is closed at precisely such a point of time that the storage of the required quantum of ignition energy will be completed at the very instant when the ignition energy is needed. Hence it is desirable to close the circuit for the ignition coil at a preceisely predetermined time prior to the point of time of ignition or firing of the spark plugs. It is common practice to determine the point of time of ignition in terms of the angular position of the crankshaft. This means that the ignition circuit must be closed at a leading angle, which angle increases as the number of revolution ofthe internal combustion engine increases.

SUMMARY OF THE INVENTION A system embodying this invention for determining the time of initiation of inductive energy storage in the ignition coil of an ignition system for internal combustion engines includes a rotatable disk driven to rotate in synchronism with an internal combustion engine, markings on said disk and fixed sensor means for reading said markings when said markings are moved past said sensor means, and discriminator means having-a predetermined threshold receiving the output of said sensor means and emitting signals whose timing is a function of the number of rpm at which said disk rotates past said sensor means. The markings on said disk are formed by lines arranged adjacent the periphery thereof and having a progressively increasing angular pitch in the direction of rotation of said disk, and the discriminator means are formed by coincidence means having two variable inputs derived from said sensor means and yielding an output in case of coincidence of said two variable inputs.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic representation of a first embodiment of the present invention;

FIG. 2 is a table of data relevant to the present inven tion;

FIG. 3, 4 and 5 are diagrammatic representations of other embodiments of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS FIG. 1 shows a rotatable disk including four quadrants I,II;,III,IV. The aforementioned disk is driven in The signal emitting disk of FIG. 1 is intended to be operatively related to a four cylinder internal combustion engine. Therefore two ignition sparks must be supplied to the internal combustion engine per revolution thereof. In order to determine the points of time at which energy storage must begin, the aforementioned quadrants [and II are provided with marks a and h which may be formed by short radially extending lines arranged close to the periphery of quadrants l and III. Reference numerals l and 2 have been applied to indicate two fixed reference points on signalling disk I,II,III,IV. The spacing between contiguous reference marks or reference lines a,b increases progressively for leading angles, or in counter-clockwise direction. The two

reference points

1,2 correspond to ignition angles of and 180 for the two cylinders which must be supplied with ignition sparks at each revolution of the crankshaft.

As shown in FIG. 1 the signalling disk 1,II,III,IV has just reached such a position that its reference point 1 between its quandrants II and III is juxtaposed to a sensor 3. The output signal of sensor 3 is supplied by two parallel lines to the input terminals of an AND-gate 4. One of these two lines interconnects sensor 3 directly with one of the two inputs of gate 4. The other of these two lines interconnects sensor 3 by the intermediary of delay line with the other of the two inputs of gate 4. The output of gate 4 is a signal initiating the storage of energy.

Supposing it is intended to use an ignition coil requiring 2 msec for storing the required quantum of ignition energy; then storage of that energy must begin at a point of time 2 msec before the crankshaft reaches a reference point, which point of time, in turn, depends upon the number of revolution of the internal combustion engine. It may be assumed that delays in the circuits are in the order of and in view thereof delay line 5 may have a delay time of 0.22 msec. The table of FIG. 2 has been calculated on the basis of the above assumptions. Column 1 of the table indicates number of revolutions per minute from 6000 down to 591. Column 2 of the table indicates for given numbers of rpm the angles a which are the angles enclosed between the

reference points

1 and 2 and the various markings on signalling disk I,II,III,IV. Column 3 indicates for given numbers of rpm the angles B which are the angles enclosed between contiguous markings on signalling disk I,II,III,IV. The angles a and ,8 have also been indicated in FIG. 1. The angles a stated in column 2 are the travel of disk I,II,III,IV at the number of rpm indicated in column 1 during a time interval of 2 msec. The same applies in regard to the angles [3 indicated in column 3 in regard to time intervals of 0.22 msec.

Assuming the crankshaft of the internal combustion engine rotates at 6000 rpm, and that the first of the marks a just passes by sensor 3. As a result, sensor 3 supplies a pair of signals to AND-gate 4, one directly,

and the other by the intermediary of delay line 5 having 7 a time delay of 0.22 msec. Since this pair of signals does not reach AND-gate 4 simultaneously, the latter has no output at this point of time. Thereafter, the next following mark a passes sensor 3, as a result of which sensor 3 supplies gate 4 with another pair of signals. Now one of the input terminals of gate 4 receives a delayed input signal resulting from the first mark on disk I,II,III,IV, and the other of the input terminals of gate 4 receives a non-delayed input signal resulting from the second mark on disk I,II,III,IV. Hence there is a coincidence of input signals at AND-gate 4, and the latter emits an output signal initiating the process of storing energy in the ignition coil of the system. All subsequent output signals of sensor 3 which follow one another at progres' sively decreasing intervals may establish conditions input coincidence at AND-gate 4, and thus cause the latter to emit output signals. This is of no consequence since it is the first output signal of AND-gate 4 which initiates the energy storage process in the ignition coil, and since the subsequent output signals of AND-gate 4 have not effect on that process, i.e. do not interrupt or disturb the same.

When the number of revolutions per min. is less than 6000, the time interval between the signals of the sensor 3 resulting from the first mark a and the second mark a is so long that the delayed signal resulting from the first mark a has disappeared at one of the inputs of gate 4 at the time when the non-delayed signal resulting from the second mark a arrives at the other of the inputs of gate 4. Then no output signal is emitted from gate 4. Under such circumstances a coincidence of a delayed signal resulting from one mark a with a nondelayed signal resulting from a subsequent mark a will occur only at smaller leading angles of disk I,II,III,IV and its driving crankshaft, respectively.

Upon termination of the energy storage or loading period reference mark 1 and sensor 6 cooperate to produce an ignition or firing signal.

The next energy storage or loading period is determined by the passage of marks b near sensor 1 in substantially the same fashion as the first energy storage or loading period has been determined.

In instances where the ignition coil forms part of a blocking oscillator the output of AND-gate 4 is used as a trigger signal for the blocking oscillator which generates the ignition spark following a period of time determined by the time constant thereof.

There are instances where it is desirable to actively control the release of ignition energy from the ignition coil and it may be acceptable to allow the flow of a holding current of limited magnitude and to interrupt the flow of that current at the point of time of ignition. In such instances marks of

reference points

1 and 2 may generate signals in sensor 6 which, in turn, cause interruption of the holding current or triggering of a thyristor.

It is apparent from the above that in the embodiment of the invention shown in FIG. I intended for a four cylinder internal combustion engine marks a and b are arranged in the first quadrant I and in the third quadrant III of disk I,II,III,lV at and 0, respectively, which marks determine jointly with

sensors

3 and 6 the beginning of the energy storage time and the ignition time. The delay line 5 causes a delayed coincidence between two signals resulting from two consecutive marks. The same principle, namely the determination of delayed coincidence of two signals to determine the point of time of initiation of energy storage, or ignition coil loading, may be embodied by other means than those shown in FIG. 1, e.g. by the means shown in FIG. 3.

Referring now to FIG. 3, the same reference characters have been applied in that figure as in FIG. 1 to indicate like parts. Hence the system of FIG. 3 calls for description only of such elements thereof which differ from those of the system shown in FIG. I. The principal difference'betweenthe system of FIG. I and that of FIG. 3 resides in'the" fact that'inthesystem of FIG. 3 the individual marks a and b whichcorrespond to each other: are not angularly displaced exactly 180%The 24 marks b of FlGJ-3 encompass an angular, range which corresponds to'that of 23 marks in the system of FIG. .1. Furthermore a sensor has been added towhich reference character 10 has been applied. Sensor 10 isarranged at the 270 position of four quadrant disk I,II,III,IV. In the system of FIG. 3 th e'delay line 5 and the AND gate 4 of FIG. 1 have been dispensedwith, or eliminated. The outputs of

sensors

3 and 6 form the inputs of a coincidence module 11. Referring to FIG. 3 and comparing the same with FIG. 1, in the former the reference marks 1 and 2 have been angularly displaced 90 relative to the markings a and b, respectively.

As mentioned above, markings a,b are not angularly displaced 180 but have a smaller angular displacement comparable to the marks of a vernier. Hence

sensors

3 and 6 emit signals which are delayed one relative to the other. The delay times of these signals is a function of the number of rpm of disk I,II,III,IV. If two such signals coincide in time, module 11 emits a signal which initiates the storage of magnetic energy in the ignition coil. When reference marks 1 and 2 sweep passed sensor 10 an ignition or firing signal is emitted by the latter.

The circuitry of FIG. 3 is even more desirable than that of FIG. 1, primarily because it does not require delay means and hence possible variations in regard to delay times. In addition thereto the structure and circuitry of FIG. 3 makes it possible to determine in a simple way with a high degree of precision the point of time at which the energization of the ignition coil should be initiated because in the embodiment of FIG. 3 the number of marks on disk I,II,III,IV may be increased, and the coincidence times of module 11 shortened.

The embodiment of the invention shown in FIG. 3 is particularly suitable to be used in conjunction with ignition coils forming part of a blocking oscillator to adjust the angles of ignition as a function of the number of revolutions per minute of the internal combustion engine. The desired adjustment of the firing angle may be achieved merely by positioning the marks on disk I,II,III,IV. On the other hand, the resolution of coincidence module 11 may be varied as, for instance, by means of a discriminator, the exact firing time depending upon the resolution of module 11.

In the embodiments of the invention which have been described above the measured quantity was the time relation between two marks. In one embodiment of the invention the time relation was ascertained by coincidence of a signal resulting from one mark and of a delayed signal resulting from a previous mark. In another embodiment of the invention the time relation was ascertained by means of two signals which were generated by two marks each pertaining to one group of marks. The discriminator required in such an instance is a time discriminator and the threshold value to be adjusted by it is the resolution of coincidence module 11.

There are, however, still other ways to achieve the desired end. It is well known that the voltage which is induced in a winding or coil is proportional to the rate of change of a magnetic flux. If marks on a rotating disk are formed by magnetic teeth or the like, the voltage pulses induced in a magnetic sensor cooperating with the disk are proportional to the number of rpm at which the disk is rotated past: the sensor. The spacing between magnetic teeth of a disk and an electromagnetic sensor may vary, e.g. the length or height of such teeth may decrease the larger the leading angle thereof.

' It is possible to generate by means of such an arrangement signals which depend upon the respective number of rpm of the disk and may be used for controlling the point of time of initiation of energization of an ignition coil. Considering a disk whose leading magnetic teeth have a relatively small height, resulting in a relatively large spacing from a cooperating electromagnetic sensor, and whose trailing magnetic teeth have a relatively small height, resulting in a relatively small spacing from a cooperating electromagnetic sensor. In such an arrangement a leading magnetic tooth of relatively small height rotating past an electromagnetic sensor at a relatively large distance may be capable of generating in the latter a sufficiently high voltage pulse to cause initiation of energization of an ignition coil.

Another possibility consists in providing the rotatable disk with marks in the shape of a train of waves having a wave length that increases progressively as the leading angle from a fixed reference point increases. As the disk rotates the train of wave marks is sensed by a fixed sensor and converted into a corresponding electric signal. The latter is supplied to a narrow band-pass filter which passes a signal if, and only if, the product of angular velocity of the disk and the wave length of its marks lies within the band of frequencies passed by the filter.

The means by which the marks on the rotating disk are sensed by the sensors has no immediate bearing on the present invention. The marks on the disk may be scanned either electro-optically, or inductively. The output signals of the sensors may be processed either by analog means or by digital means. The threshold discriminators applied in embodying the present invention may be time discriminators, voltage discriminators, or current discriminators, the particular kind of discriminators used being dependent upon the particular circumstances under consideration.

I claim as my invention:

1. In an ignition system for internal combustion engines including means for inductively storing and for controlling the point of time of initiation of energy storage including in combination a. a rotatable disk driven to rotate in synchronism with an internal combustion engine;

b. markings on said disk and fixed sensor means for reading said markings when said markings are moved past said sensor means;

0. discriminator means receiving the output of said sensor means and emitting signals whose timing is a function of the rpm at which said disk rotates past said sensor means;

2. An ignition system as specified in claim 1 wherein markings on said disk cooperate with additional fixed sensor means emitting timing signals for energy release from the inductive storage thereof.

3. An ignition system as specified in claim 1 wherein said coincidence means are formed by an AND-gate having two inputs of which one input is supplied directly from a marking sensor and the other input is supplied from said marking sensor by the intermediary of a delay line.

4. In an ignition system for internal combustion engines including means for conductively storing ignition energy and for controlling the point of time of initiation of energy storage the combination of a. a rotable disk driven to rotate in synchronism with an internal combustion engine;

b. markings on said disk and fixed sensor means for reading said markings when said markings are moved past said sensor means, said markings being formed by lines arranged immediately adjacent to the periphery of said disk and having a progressively increasing angular pitch in the direction of rotation of said disk; and

c. discriminator means receiving the output of said sensor means and emitting signals whose timing is a function of the number of rpm at which said disk of said pair of sensors.

Claims

1. In an ignition system for internal combustion engines including means for inductively storing and for controlling the point of time of initiation of energy storage including in combination a. a rotatable disk driven to rotate in synchronism with an internal combustion engine; b. markings on said disk and fixed sensor means for reading said markings when said markings are moved past said sensor means; c. discriminator means receiving the output of said sensor means and emitting signals whose timing is a function of the rpm at which said disk rotates past said sensor means; d. said markings on said disk being formed by lines arranged adjacent to the periphery of said disk and having a progressively increasing angular pitch in the direction of rotation of said disk; and e. said discriminator means being formed by coincidence means having two variable inputs derived from said sensor means and yielding an output in case of coincidence of said two variable inputs.

4. In an ignition system for internal combustion engines including means for conductively storing ignition energy and for controlling the point of time of initiation of energy storage the combination of a. a rotable disk driven to rotate in synchronism with an internal combustion engine; b. markings on said disk and fixed sensor means for reading said markings when said markings are moved past said sensor means, said markings being formed by lines arranged immediately adjacent to the periphery of said disk and having a progressively increasing angular pitch in the direction of rotation of said disk; and c. discriminator means receiving the output of said sensor means and emitting signals whose timing is a function of the number of rpm at which said disk rotates past said sensor means, said discriminator means being formed by a coincidence gate having two inputs, one of said two inputs being directly supplied by the output of said fixed sensor means and the other of said inputs being supplied by said fixed sensor means by the intermediary of a timedelay line.

5. An ignition system as specified in claim 1 including a pair of angularly displaced sensors, a coincidence module supplied with the outputs of said pair of sensors and two angularly displaced groups of markings on said disk, each arranged to be read simultaneously by one of said pair of sensors.