JPS5831472B2 - Digital heating system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a digital circuit arrangement for starting the ignition process of an internal combustion engine at a crankshaft angle determined by the operating parameters of the internal combustion engine.

In internal combustion engines, the ignition angle must be adjusted as a function of the rotational speed and the load on the internal combustion engine, and possibly also as a function of other operating parameters of the internal combustion engine.

This is because the spark plug initially ignites only the air-fuel mixture that is in the immediate vicinity of the spark plug.

The front of the flame then passes through the cylinder at approximately constant speed to ignite the remaining mixture.

It always takes approximately the same amount of time for the flame front to reach the cylinder wall, regardless of the engine speed.

The maximum combustion pressure must be adjusted immediately after the piston passes top dead center (OT).

Therefore, in the case of an ignition plug, the higher the rotational speed of the internal combustion engine, the farther before the top dead center the ignition spark occurs when viewed from the crankshaft angle.

As a result, the traveling time of the front side of the flame is compensated to be constant.

Moreover, the velocity of the flame front varies depending on whether the fuel-air mixture is more or less concentrated and thus how easy it is to ignite the mixture.

When the load on the internal combustion engine is large and the throttle valve is wide open (low intake pipe load), the air-fuel mixture supplied to the cylinder is sufficient and ignition is easy, and the flame front spreads rapidly.

Ignition therefore takes place relatively late. On the other hand, if the load on the internal combustion engine is low and the throttle valve is significantly closed, the mixture supply in the carburetor is so small that the flame front can only expand at a low speed.

Ignition therefore occurs early. Therefore, when the ignition angle is far before the top dead center, this is called early ignition.
When the ignition angle is slightly before top dead center or after top dead center, this is called ignition delay.

Normally, suction pipe negative pressure is used as a measure of the load applied to the internal combustion engine, and this negative pressure is measured using a negative pressure measuring box.

In conventional ignition circuits, the rotational speed is measured mechanically using a centrifugal weight.

As an alternative to conventional mechanical ignition angle adjustment devices, various electronic circuit devices are already known which operate without wear.

Many of the circuits are constructed using analog circuit technology, in which the rotational speed and suction tube negative pressure are converted into variable amounts of DC voltage.

The disadvantage of this analog circuit technique is that, before the firing angle adjustment circuit is put into operation, extensive adjustment work must be carried out to match the voltage levels of each stage of the circuit to each other.

Therefore, it is necessary to compensate for variations in each of several component elements.

In addition, the analog circuit has the disadvantage of slow operating speed.

Digital circuit arrangements for adjusting the ignition angle are already known, in which a counter counts the output pulses of a pulse speed generator for a predetermined period of time in order to determine the speed of the internal combustion engine.

The counting period is determined by a monostable multi-vibration brake which delivers pulses with varying pulse widths depending on the suction tube underpressure and possibly other operating parameters.

The circuit arrangement is therefore only partially digital and has the aforementioned disadvantages of analog circuit technology in terms of monostable multi-bibreak stages.

Moreover, it is extremely difficult to relate two or more operating parameters to the adjustment of the pulse width of a monostable multi-bibreak.

In known semi-digital circuit arrangements, the ignition angle is determined by a counting process carried out in two parts.

For example, the first counting process part is 1800 meters from the top dead center.
The output pulses of the open speed generator are counted for a time determined by the monostable multi-by-break, starting at

The counter state takes on a larger value as the rotation speed increases.

The counting process then continues, for example at 45° before top dead center, and when a predetermined number of counting pulses is reached, the counting process is completed and the ignition process is started.

The greater the number of pulses that are counted during the rotational speed measurement, the fewer the number of pulses that must be counted in the second counting process part.

In other words, a high rotational speed means that ignition occurs earlier.

In this counting method, since the rotational speed is detected only once for every revolution of the crankshaft, large operational errors occur when the rotational speed of the internal combustion engine changes rapidly.

This means that when the ignition process is started after a further half revolution of the crankshaft, the rotational speed of the internal combustion engine has already changed, possibly significantly.

The object of the present invention is therefore to provide a digital circuit arrangement for starting the ignition process of an internal combustion engine at a crankshaft angle determined by the operating parameters of the internal combustion engine, which consists entirely of components of digital technology. Moreover, it is an object of the present invention to provide a device configuration in which operational errors during rotational speed measurement are reduced as much as possible.

In order to solve this problem, according to the present invention, in the apparatus of the type mentioned at the beginning, a rotational speed generator for sending out a signal train and a period counter supplied with the signal train sent out from the rotational speed generator are provided. an oscillator whose oscillator frequency varies depending on at least one parameter of the internal combustion engine is connected upstream to the counting input of the period counter, and pulses from the oscillator are supplied to the period counter. In order to determine (measure) the time interval of a signal from the speed generator which is such that the speed generator is a reference value for the speed of the internal combustion engine, and which is a reference value for the speed of the internal combustion engine, the time interval between one and two successive speed generator signals is determined. During a time interval, further signal sequences from the oscillator are counted in a period counter and stored as binary numbers in an end-state memory, distributed over the crankshaft angle in accordance with the desired speed characteristic. The ignition process is started by evaluating and counting the binary numbers via a characteristic curve generator which generates pulses.

In other words, the crankshaft of an internal combustion engine has two separate pulse generators: a rotation speed generator that sends out output pulses at uniform intervals with respect to the shaft angle, and a crankshaft that advances according to the desired rotation speed characteristics. The characteristic curve generating device is configured to send out pulses at different intervals depending on the shaft angle.

Since the rotation speed generator generates a large number of pulses each time the crankshaft rotates, operational errors in rotation speed measurement can be reduced almost arbitrarily.

With each new pulse generated by the speed generator, new speed information appears in the end state memory.

By means of the characteristic curve generator, any desired speed characteristic curve can be generated for the internal combustion engine used.

In an exemplary embodiment of the invention, this is done by adding up the pulses generated according to the desired speed characteristic in a counter, so that finally in the characteristic curve counter there is a count of the characteristic curve. A binary number appears that is a measure of the crankshaft angle advanced since the start.

Although the characteristic curve generator is shown in the exemplary embodiment as a mechanical generator, binary numbers of this type can in principle also be retrieved from a ROM, whose storage locations are selected as a function of the rotational speed. .

As an alternative, the characteristic curve generator can therefore be designed purely electronically.

In different embodiments of the rotating device according to the invention, other operating parameters can be taken into account purely digitally, for example the initial state of the period counter and the initial state of the characteristic curve counter can be varied.

A particularly simple embodiment, taking into account the negative pressure in the suction pipe, consists in varying the counting frequency of the period counter.3 Advantageous embodiments of the invention will now be explained in detail with reference to the embodiment shown in the figure. In FIG. 1, the rotational speed generator is indicated by 10.

The generator has a gear 11 driven by the crankshaft of an internal combustion engine, the ferromagnetic teeth of which pass by a magnetic core 12 as gear 11 rotates.

A coil 13 is wound around the magnetic core 12.

One terminal of the coil 13 is connected to ground, and the other terminal forms the output side of the rotational speed generator 10 .

A pulse shaping circuit 14 consisting of a differentiating circuit 15 and a Schmitt trigger circuit 16 is connected downstream of the rotational speed generator 10 .

This differential circuit 15 has a differential capacitor 17, one connection terminal of which is connected to the output side of the rotational speed generator 10, and the other connection terminal connected to a resistor 18. Connected to ground through.

A diode 19 is connected between the connection point between the capacitor 17 and the resistor 18 and the input side of the Schmitt trigger circuit 16.

The negative pressure measuring box 20 is connected via a conduit 21 to an intake pipe of an internal combustion engine (not shown).

Negative pressure measuring box 20 moves ferrite core 23 through high frequency coil 24 via connecting member 22 .

The high frequency coil 24 and the capacitor 25 constitute a parallel oscillating circuit, which determines the oscillating frequency of the oscillator 26.

The output side of the oscillator 26 is the counting input side Z of a period counter 27 (or rotation period counter, hereinafter simply referred to as period counter).
It is connected to the.

The set input 1 of the period counter 27 is connected to the output of the Schmitt trigger circuit 16.

The binary output of the period counter 27 is connected to the input of the end state memory 28 .

The set input 1 of this memory is connected via an inverting stage 29 to
It is connected to the output side of the Schmitt trigger circuit 16.

The characteristic curve generator 30 , like the rotational speed generator 10 , has a gear 31 driven by a crankshaft, the ferromagnetic teeth of which pass by a magnetic core 32 .

The teeth of the gear 11 are uniformly distributed around the outer periphery of the gear, while the teeth of the gear 32 are uniformly distributed around the outer periphery of the gear.

A coil 33 is wound around the magnetic core 32, and one connection terminal of the coil 33 is connected to ground.

The other connection terminal of the coil 33 constitutes the output side of the characteristic curve generator 30 and is connected to the input side of a Schmitt trigger circuit 34 which is used as a pulse shaping quantity.

The output of the Schmitt trigger circuit 34 is connected to a counting input Z of a characteristic curve counter 35.

The set input 1 of the characteristic curve counter 35 is connected to the output of a reference pulse generator constituted by a switch 36 .

The switch 36 is periodically opened and closed by a cam 37 in synchronization with the crankshaft rotation speed.

The dashed line 38 shows that both gear wheels 11.31 as well as the cam 37 are driven by the crankshaft of the internal combustion engine.

The binary output of the characteristic curve counter 35 and the output of the end state memory 28 are connected to two binary inputs of a binary comparator 39.

The output side of comparator 39 is connected to the input side of power amplifier 40.

Furthermore, two initial state stores 41, 42 are provided, of which the first store 41 is connected to the binary input of the period counter 27, and the second store 42 is connected to the characteristic curve. It is connected to the binary input side of the counter 35.

Both initial state memories 41 and 42 are configured as fixed memories (read-only memories ROM) and contain binary numbers Z.
Address input side 43 to 4 where a to zb are input
It is equipped with 4.

Binary numbers Za and zb are shown schematically as three-digit binary numbers.

One digit of the binary number zb is determined by the output signal of the limit value switch 45.

The input side of this limit value switch 45 is connected to a tap of a voltage divider constituted by a resistor 46 and a resistor 47 having a negative temperature characteristic.

The resistor 47 with negative temperature characteristics is in thermal contact with the engine block of the internal combustion engine.

One digit of the binary number Za is determined by whether the start switch 48 is closed or opened.

Another digit of the binary number Za is a switch 4 that opens and closes depending on the output signal of an exhaust gas measuring sonde (not shown).
Determined by the position of 9.

The remaining digits of the binary numbers Za and zb are used, for example, to take into account the temperature of the engine block with greater precision and to adjust the ignition angle in stages as a function of this temperature.

In the coil 13 of the rotation speed generator 10, the gear 11
When the ferromagnetic teeth of the magnetic core 12 pass by the magnetic core 12, an alternating current voltage pulse is induced.

The frequency of this alternating voltage pulse is proportional to the rotational speed of the internal combustion engine.

Differentiator circuit 15 is used to form needle-shaped pulses with very close edges from the alternating voltage pulses of rotational speed generator 10 .

Diode 19 passes only the positive needle pulse to the Schmidt
The signal is passed through the trigger circuit 16.

This Schmitt trigger circuit forms a very narrow rectangular pulse from a needle pulse.

The pulse width of this rectangular pulse must be smaller than its pulse interval.

This condition does not have to be fulfilled so strictly in the characteristic curve generator 30; the Schmitt trigger circuit 34 is therefore connected directly to the output of the coil 33.

The oscillator 26 is configured as an Lc oscillator (eg a Hartley or Colpitts oscillator).

A parallel oscillating circuit 24,25 determines the oscillating frequency of the oscillator 26.

If the vacuum in the suction pipe is high, ie the throttle valve is closed significantly, the vacuum measuring box 20 is exposed to outside air pressure.

This measuring box then draws the ferrite core further into the high frequency coil 24 via the connecting member 22.

As a result, the inductance of the coil 24 increases and the vibration frequency of the oscillator 26 decreases.

Therefore, the lower the negative pressure in the suction pipe or the larger the negative pressure in the internal combustion engine, the higher this vibration frequency becomes.

In the embodiment shown in FIG. 1, the ferrite core 23 has a conical shape.

By configuring it in such a shape, it is possible to prevent the vibration frequency of the oscillator 26 and the negative pressure of the suction pipe from having a linear relationship.

In short, any negative pressure characteristic curve can be formed depending on the shape of the core 23.

Counter 27.35 and memory 41.2 shown in FIG.
8.42 and the binary comparator 39 are commercially available as integrated circuit parts.

Component 5N74191 as counter 27.35, component 5N7475 as memory 28 and binary comparator 3
Component 5N7485 is used as 9.

Correction amounts Za and Zb are not used, so the address input side 33
．． 34 is not required, the initial state memory 41.4
Component 5N7475 may also be used as 2.

On the other hand, if different binary numbers Za and Zb are to be considered as the initial state of the counter 27.35 depending on the operating conditions, a fixed memory (ROM) is used as the memory 4L42.

In the experimental circuit, if you want to change the stored values of the memories 41 and 42 belonging to different binary numbers Za and Zb many times, use a programmable fixed memory (FROM, for example, Intel 1702) as the memory 41 and 42. use.

The fixed memory or programmable fixed memory receives from its output the binary number Za which is supplied to the address input.
A binary number whose value is determined by zb or zb is sent.

The number of digits of the output binary number can be matched to the number of digits of the counter 27.35.

FIG. 2 shows a rotational speed adjustment characteristic curve 50, which shows how it is formed by a centrifugal weight in a mechanical ignition angle adjustment device.

The ignition angle is indicated by α2, and indicates the position from top dead center measured in angle.

Three types of dimensions are scaled on the abscissa in FIG.

What is scaled at the top is the rotational speed n, U/m1n (revolutions per minute).

The second scale is the rotational speed n in U/sec
(revolutions per second) or Hz.

Finally, the third scale is the period T required for one revolution, in ms.

In the tuning characteristic curve shown in FIG. 2, the ignition angle is 10
At low rotational speeds up to 00 rotations, it is initially constant.

The ignition angle then rises steeply up to a speed of 3200 revolutions per minute, and above 3200 revolutions per minute the rate of rise becomes more flat.

FIG. 3 shows a rotation speed adjustment characteristic curve 51 obtained from the characteristic curve 50.

In this case, however, the ignition angle α2 is shown as a function of the period T, which is linearly graduated on the abscissa.

From 60 m5 onwards, the adjustment characteristic curve has a constant value of 10 for dog periods.
Take °.

In contrast, the characteristic curve realized by the circuit of FIG. 1 shows a flat drop, as indicated by the dashed line 52.

Such a flat descent is advantageous, since at very low engine speeds the ignition angle shifts further in the direction of ignition delay.

However, such a suitable drop cannot be achieved with a centrifugal weight, since a sufficiently large centrifugal force is still not generated at such a low rotational speed.

The regulating characteristic curves 51, 52 shown in FIG. 3 are formed by the circuit shown in FIG.

The ignition angle adjustment therefore takes place in relation to the period (or rotational period), and not in relation to the rotational speed, as is the case with conventional adjusting devices.

FIGS. 4 and 5 show how the period counter 27 captures the time intervals of the pulses of the rotational speed generator 10 and at the same time takes account of the suction pipe negative pressure.

In the circuit shown in FIG.
It is assumed that the action of the negative pulse edge on the set input 1 causes the respective number to be transferred to the binary input.

That is, from the Schmitt trigger circuit 16, the inverting stage 29
As soon as the leading edge of the pulse that is inverted at is emitted, the counter end state of the period counter 27 is transferred to the end state memory 28.

The pulses of the Schmitt-Trial circuit 16 last only for a very short time and with their edges, the binary number ZOI sent out from the initial state memory 41 is transferred to the period counter 27.

The counter state of the period counter 27 is indicated by 2 in FIG. is counted in the direction of decreasing magnitude.

Pulses are emitted from the rotational speed generator 10 at times T1 to T4.

The time interval is constant for the first three pulses, but the fourth
From the second pulse, the rotation speed increases at time T4,
The pulse interval shall be correspondingly shortened.

The diagram in Figure 5 shows the same rotational speed state, but the difference between the diagram in Figure 4 and the diagram in Figure 5 is that in Figure 5, the load applied to the internal combustion engine is higher. 4, so that the counting frequency delivered by the oscillator 26 is higher than in the case of FIG.

In the case of Fig. 4, since the counting frequency is low, the period counter 27
shows the counter end state Z1 which is relatively high in each case upon the arrival of pulses T1 to T3.

This final state is transferred to the final state memory 28, and the counter 2
8 is again set to its initial state Z01.

The fourth pulse T4 of the rotational speed generator has a smaller spacing from the preceding pulse, so that the counter 28 also assumes a higher end state Z3, which end state at the time T4.
4, the information is transferred to the final state memory 28.

In the case of the diagram of FIG. 5, the counting frequency is higher and the counter 27 exhibits a low counter state Z2 for the first speed generator pulses T1 to T3, but slightly lower for the fourth speed generator pulse. The higher counter state Z4 is shown.

In short, the counter end states Z1 to Z4 are, on the one hand, a measure of the rotational speed of the internal combustion engine and, on the other hand, a measure of the suction pipe underpressure.

FIG. 6 shows how the ignition angle α is determined by the characteristic curve counter 35 from the counter end states Z1 to Z4 of the period counter 27.

The characteristic curve counter 35 is connected to the switch 3 of the reference pulse generator.
6 (negative pulse side edge) sets the initial state ZO2.

This initial state ZO2 is sent out from the initial state memory 42.

This set of counters 35 forms an angle α0 of 42° before the top dead center.
What is done is shown in Figure 6.

The characteristic curve generator 30 starts delivering pulses 40° before top dead center.

The characteristic curve generator is likewise designed as a backward counter.

The steep course of the speed adjustment characteristic curve 51 shown in FIG. 3 means that the ignition angle α
Significant changes such as those shown in FIG. 2 are achieved by increasing the angular spacing of the teeth of gear 31.

If, on the other hand, the characteristic curve 51 shown in FIG. 3 is to have a flat course, the teeth of the gearwheel 31 must be arranged at significantly smaller distances from each other.

From the shape of the teeth of the gear 31 shown in FIG. 1, it can be seen how the adjustment characteristic curve shown in FIG. 3 is formed.

The first three teeth are relatively closely spaced, since they form the part of the flat characteristic curve between T=10 ms and T=20 ms.

This is followed by a section of the characteristic curve that is steeper and the teeth are spaced further apart.

The teeth then close together again, forming the part of the characteristic curve up to T-60 ms, and approach very closely in the terminal part, since the characteristic curve must run as flatly as possible in this part. It is from.

The gear wheel 31 shown in FIG. 1 is only schematically shown, since in this case the teeth are arranged over an angular range of more than 180°, whereas in the embodiment shown in FIG. Angular range from 40° to 10° before dead center,
That is, this is because they must be arranged over approximately 300 locations.

However, when a high degree of angular resolution is required - as shown in Figure 1 - the transmission ratio allows the teeth of gear 31 to travel faster than the crankshaft so that the teeth of gear 31 are spread over a larger angular range. It is good to place it.

In the counting curve of the characteristic curve counter shown in FIG. 6, the part where the adjustment characteristic curve shown in FIG. 3 curves flat becomes steep or vice versa because the tooth spacing changes.

When the rotation speed is high, that is, the period T is small, the period counter 27
indicates a counter final state that differs only slightly from the initial state ZOI.

There, the counting curve of the characteristic curve counter 35 shown in FIG. It does not change.

The counting curve shown in FIG. 6 reaches the counter end state Zl (see FIG. 4) for an ignition angle α2 of approximately 18° before top dead center.

At this moment the numbers supplied to the binary comparator 39 have the same value and the comparator 39 sends out a pulse which is amplified in a power amplifier 40 and supplied to the ignition device.

When the load is high or the suction pipe pressure is low as shown in Figure 5, even if the rotation speed is the same, the final state Z of the counter will be lower.
2 occurs.

Ignition therefore occurs only when the curve shown in FIG. 6 reaches the value Z2, ie at an ignition angle Z of about 11° before top dead center
It will be held in

This is because, as already mentioned, when the load is large, an easily ignitable air-fuel mixture exists and the traveling time of the front side of the flame is short.

Although the embodiment of FIG. 1 uses electromagnetic generators 10 and 30, which have limited angular resolution compared to optical generators, optical generators may alternatively be used. .

In the illustrated electromagnetic generator 10.30, gears 11 and 31
A maximum of approximately 120 teeth are provided on the outer circumference of the tooth with a mutual angular spacing of 3°.

According to FIG. 6, the accuracy of the resolution of the ignition angle αZ is
Determined by the tooth spacing of 1.

Even when setting a rotational speed transmission ratio of 4 times to the crankshaft, the angular resolution obtained with the most densely arranged teeth is only about 0.8°.

In the steep region of the rotational speed adjustment characteristic curve shown in Figure 3,
The teeth of gear 31 are spaced further apart, so that in this region only an angular resolution of about 5° is obtained, but this resolution is retained regardless of the lifetime and is therefore incomparable to mechanical ignition angle adjustment devices. already represents significant progress.

However, if it becomes necessary to make further use of the possible precision of the digital circuit arrangement, the electromagnetic generators 10, 30 can be replaced by photoelectric generators.

Generators of this type are known: in the beam path between the light source and the photocell, a disk is run which has transparent and non-transparent areas that alternate with each other.

As the disk rotates, a voltage pulse is generated across the photocell.

120 on the periphery of the disc without the same difficulty as on the left.
Zero non-transparent marks can be placed, so the accuracy of the angular resolution is ten times greater than that of an electromagnetic generator.

FIG. 7 shows an embodiment of such a disk for use in a photoelectric speed and characteristic curve generator.

This disk rotates about an axis 53 in the direction of the arrow.

Three generator tracks 54 are located at the periphery of this disk.
°55.56 is provided.

Three photocells are arranged in the three generator tracks.

The beam path traveling from the light source to the photocell passes through the transparent disk at 57 and 5B in FIG.

It is indicated by 59.

The first generator track 54 operates in conjunction with the first photocell as a reference pulse generator and thus replaces the cam 3T and switch 36 shown in FIG.

The second generator track 55 together with the photocell 58 forms the pulse speed generator 10 shown in FIG.

Finally, the third generator track 56 connects the third photocell 5
9 forms a characteristic curve generator.

The third generator track 56 is marked with two sets of homogeneous series of generator marks connected to the tooth positions of the gear wheel 31 .

The series of marks in both sets are each applied over an angle of approximately 90 DEG or more, ie the marks are enlarged twice in angle compared to the counting characteristic curve shown in FIG.

Therefore, the disk shown in FIG. 7 must rotate at twice the rotation speed of the crankshaft.

This disk is also marked for two reference pulses in the first generator track 54, so that this disk generates four pulses for setting the characteristic curve counter 35 for each revolution of the crankshaft. and transmits four characteristic curve pulse trains.

Therefore, four ignition pulses are generated per crankshaft revolution.

This is necessary for an 8 cylinder engine.

It is of course also possible to simply span both sets of characteristic curve indicator marks in the third generator track 56 over an angle of about 40 to 45 DEG and drive the disk directly at the crankshaft speed.

Other transmission ratios are also possible.

Just consider the number of cylinders in each case and the desired angular resolution.

The disc shown in FIG. 7 delivers a reference pulse which sets the characteristic curve counter 35 to its initial state ZO2 at a crankshaft angle of 45 DEG before top dead center.

In this case, at about 43° before the top dead center, the characteristic curve counter 35
The marking of the third generator track begins, which generates counting pulses for .

In this case, the spacing between the marks follows approximately the same relationship as the spacing between the teeth of gear 31 shown in FIG.

In this case it continues beyond this mark or top dead center OT.

In other words, when starting at room temperature, such slow ignition becomes a problem.

If the engine block temperature is extremely low, the resistor with a negative temperature characteristic (see FIG. 1) assumes a significantly high value, so that the limit value switch 45, configured as a Schmitt trigger circuit, is switched and accordingly the initial state memory 42 is switched. The binary number zb applied to the address input 44 of is changed.

The initial state store 42 therefore delivers a binary number significantly larger than Zo2.

Therefore, the counting characteristic curve shown in FIG. 6 is moved upwards,
The ignition angle is shifted in the direction of the ignition delay at any rotational speed.

In this case, the shift of the characteristic curve shown in FIG. 6 is of such a magnitude as to result in an ignition angle αZ located behind top dead center.

Therefore, the markings on the third generator track 56 also continue beyond top dead center.

In special cases, the ignition angle may also be adjusted in the direction of the ignition delay even during the starting process.

For this purpose, in the circuit shown in FIG. 1, a starting switch 48 is connected to the address input 43 of the initial state memory 41.

While the starting switch 48 is closed, a further address binary number Za is applied to this address input 43 and the initial state Zol of the period counter 27 is shifted to a lower value.

In FIGS. 4 and 5, therefore, necessarily lower counter end states Z1 to Z4 are obtained.

This lower end state of the counter is also obtained by the counting characteristic curve shown in FIG. 6 only with a delay, so that the ignition angle is shifted as required in the direction of the ignition delay.

In the same way, by opening and closing the switch 49, the ignition angle can be shifted, depending on the composition of the exhaust gas, in the direction of an earlier or later ignition, as required.

By inputting to a plurality of address input sides of the initial state memory 41, it is also possible to change the ignition angle in multiple steps depending on the composition of the exhaust gas.

It is also possible to provide an oscillator 26 with a fixed output frequency.

In this case, in order to take into account the suction pipe negative pressure, the negative pressure measuring box 20 is used, and the address input side 43 to 44 are sequentially
Multiple switches connected to the switch can be closed.

In this case, the suction pipe negative pressure directly influences the initial state of the counters 27 and 35 via the address binary numbers Z, a to zb.

Although the circuit outlay is less than that of the variable frequency oscillator 26, the suction pipe underpressure is only taken into account in several stages and not continuously.

In the embodiment shown in FIG. 1, the output frequency of oscillator 26 is on the order of 100 kHz; this frequency varies, for example, between 80 kHz.

In selecting the angular spacing of the rotational speed generator marks on the second generator track 55 shown in FIG.
The choice is made such that 6 delivers approximately the same number of pulses from mark to mark as are contained in the characteristic curve series of generator marks.

In the embodiment shown in FIG.
16 rotation speed generator marks are provided on the .

Since the disc rotates at twice the speed of the crankshaft, at a no-load speed of 600 revolutions per minute, the time interval of the revolution generator pulses is approximately 3 ms, which is 6000 revolutions per minute.
At maximum speed of rotation, the time interval is approximately 0.3 ms.

If this time interval is counted with an oscillator frequency of 100 kHz, the period counter 27 is supplied with 300 pulses at no-load speed and 30 pulses at maximum speed.

Therefore, the initial state of the period counter 27 must be a value slightly greater than 300.

The series of characteristic curve generator marks on the third generator track 56 must likewise number approximately 300.

This is distantly related to the case of photoelectric rotational speed generators.

If the characteristic curve generator is to require a relatively small number of markings, a large number of markings corresponding to the rotational speed generator tracks 55 must be provided or a voltage divider must be connected downstream of the oscillator 26.

The pulse shaping circuit 14 shown in FIG. 1 is shown by way of example only.

Similarly, the output pulses of the coil 13 or of the photocell 58 can be converted directly into rectangular pulses, and the pulses of the rotational speed generator can then be combined in a known manner into two separate timing pulse trains.

In either case, the final state of the counter is first stored in the final state memory 2.
8, and only then must period counter 27 be set to its initial state Zol again.

That is, the circuit device described above solves the problem described at the beginning.

In this case, exclusively integrated circuit components of digital circuit technology are used, so that no adjustment work is required and no effects of capillary aging occur.

What is particularly advantageous is that there are three possible ways to take additional operating parameters into account when determining the ignition angle: firstly, the counting frequency of the period counter 27; , the address of the initial state memory 41, and third, the address of the initial state memory 42.

[Brief explanation of the drawing]

The figures explain the present invention in detail. Figure 1 is a schematic block circuit diagram of an embodiment of the invention, Figures 2 to 6 are diagrams explaining the operation of the embodiment of the invention, and Figure 7 is an optical FIG. 3 is a schematic diagram of a combination configuration of a target rotation speed and a characteristic curve generating device. 10... Pulse rotation speed generator, 11, 31.
...Gear, 12.32 ...Magnetic core, 1
3,23゜33... Coil, 14...
Pulse shaping circuit, 15...Differential circuit, 16.3
4... Schmitt trigger circuit, 20...
... Negative pressure measurement box, 21 ... Conduit, 22.
...Connecting member, 23 ... Ferrite core, 26 ... Oscillator, 27 ... Period counter, 28 ... Final state memory, 29...
Inversion stage, 30...Characteristic curve generator, 35...
... Characteristic curve counter, 37 ... Cam, 39
...Binary comparator, 40 ... Power amplifier, 41.42 ... Initial state memory, 43.4
4...address input side, 45...limit value switch, 54.55.56...generator track, 57°58.59...beam passage A place.

Claims (1)

[Claims] 1. In a digital circuit device for starting the ignition process of an internal combustion engine at a crankshaft angle determined by the operating parameters of the internal combustion engine, a rotation speed generator 10 that sends out a signal train and a signal train sent from the rotation speed generator are used. A period counter 27 is provided, upstream of which is connected to the counting input Z of the period counter 27, the oscillator 26 having an oscillator frequency that varies depending on at least one parameter of the internal combustion engine. pulses are supplied to the period counter 27, and in order to determine (measure) the time interval of the signal from the rotational speed generator, which is a reference value for the rotational speed of the internal combustion engine. During the time interval between two successive rotational speed generator signals, a further signal sequence from the oscillator 26 is counted in a period counter 27 and stored as a binary number in the end state memory 28, and its characterized in that the ignition process is started by evaluating and counting said binary numbers via a characteristic curve generator 30 which generates pulses distributed over the crankshaft angle in accordance with the desired speed characteristic. A digital circuit device for starting the ignition process of an internal combustion engine.