JP3209038B2 - Ignition device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition device for an internal combustion engine that controls the ignition position of the internal combustion engine using a microcomputer.

[0002]

2. Description of the Related Art Generally, an ignition device for an internal combustion engine has an ignition circuit for generating a high voltage for ignition when an ignition signal is given, and a timing (ignition position) for giving the ignition signal to the ignition circuit.
And a control unit for controlling the ignition timing, and applying a high voltage obtained from an ignition circuit to an ignition plug attached to a cylinder of the engine to perform an ignition operation.

In recent years, various demands have been made on internal combustion engines, such as purification of exhaust gas, improvement of fuel efficiency, reduction of noise, and improvement of output, and in order to meet these demands, a microcomputer is used. Therefore, a digital ignition device that accurately controls the ignition position of the internal combustion engine with respect to control conditions such as the number of revolutions using the control device has been required.

In an ignition device for an internal combustion engine in which an ignition position is controlled by using a microcomputer, a fixed ignition position signal for detecting a fixed ignition position which is an ignition position at an extremely low speed of the internal combustion engine and a signal from the fixed ignition position are used. A signal generator for generating at least a reference signal for detecting a reference rotation angle position set at the advanced position, and a rotation speed measuring means for obtaining data for calculating the rotation speed of the internal combustion engine; An ignition position calculating means for obtaining data for measuring an ignition position of the internal combustion engine, and an ignition signal generating means for measuring the ignition position and generating an ignition signal are realized by a microcomputer, and the ignition position of the internal combustion engine is realized. The rotation speed is controlled.

The rotation speed measuring means generates a reference clock pulse, which is generated between the generation of a reference signal at the reference rotation angle position of the engine and the generation of the next reference signal (during one rotation of the engine), by a micro clock. The data is counted by a counter provided in the computer, and the counted value is stored in the RAM as a counted value for measuring the number of revolutions.

The ignition position calculation means interpolates and calculates the ignition position for each rotation speed obtained from the rotation speed measurement count value using a map giving the relationship between the rotation speed of the engine and the ignition position. The ignition position is calculated in the form of the number of clock pulses to be counted while the crankshaft of the engine rotates from the reference rotation angle position to the ignition position, and is stored at a predetermined address in the RAM. In this specification, the count value of the clock pulse is referred to as an ignition count value.

The ignition signal generating means starts counting the ignition position measurement count value by the counter when the reference signal is generated, and generates an ignition signal when the counter completes counting the ignition count value.

[0008] Since the miniaturization and cost reduction of an ignition device for an internal combustion engine are strictly required, components such as an MPU, a ROM, a RAM, a counter and the like are usually constructed in one chip as a microcomputer. A so-called one-chip microcomputer is used.

[0009]

In the ignition device for an internal combustion engine as described above, in order to accurately control the ignition position with respect to the rotation speed, the count value for measuring the rotation speed and the count value for ignition must be 16 times. It must be treated as a binary number of bits. In the conventional igniter, the count value for measuring the number of revolutions and the count value for ignition are each counted using a 16-bit counter. Therefore, it is necessary to use an expensive microcomputer having a built-in 16-bit counter as a microcomputer. There was a problem that becomes high.

It is an object of the present invention to provide an ignition device for an internal combustion engine in which an ignition position can be accurately controlled by a microcomputer using an inexpensive 8-bit counter.

[0011]

According to the present invention, there is provided an ignition circuit for generating a high voltage for ignition when an ignition signal is applied;
A microcomputer and at least a fixed ignition position signal for detecting a fixed ignition position of the internal combustion engine and at least a reference signal for detecting a reference rotation angle position set at a position advanced from the fixed ignition position. A number of reference clock pulses generated during one revolution of the internal combustion engine to obtain a count value for measuring the number of revolutions consisting of a 16-bit binary number; and a reference rotation angle. The ignition position at which the number of clock pulses to be counted during rotation of the engine from the position to the rotation angle position corresponding to the ignition position of the internal combustion engine is calculated for each rotation speed as a 16-bit binary count value for ignition. A microcomputer realizes an arithmetic means and an ignition signal generating means for generating an ignition signal by counting an ignition count value so that the ignition position of the internal combustion engine can be controlled with respect to the rotation speed. Those related to the ignition device for an internal combustion engine for controlling Te.

In the present invention, the microcomputer performs a counting operation at a predetermined reference clock frequency.
A counter having a first bit counter and an 8-bit second counter that performs a counting operation at a frequency obtained by dividing the reference clock frequency by a set division ratio is used.

In the present invention, the rotation speed measuring means clears the first counter every time the reference rotation angle position is detected by the reference signal, and a predetermined number of RAMs provided in the microcomputer. A carry storage unit that uses the address as a carry bit storage memory and increments the storage content of the carry bit storage memory by one each time the first counter completes a total counting operation;
Upper 8 bits of the rotational speed measurement count value obtained from the storage contents of the carry storage means immediately before the counter is cleared, and the lower 8 bits of the rotation speed measurement count value obtained from the count value of the first counter. Is stored.

Further, the ignition signal generating means is provided with the upper 8 bits of the 16-bit ignition count value calculated by the ignition position calculating means.
It is determined whether the bit is 0 or 1 or more, and when it is determined that the upper 8 bits of the ignition count value is 1 or more, the ignition is continued until the upper 8 bits of the ignition count value becomes 0. Count value shifting means for shifting each digit of the count value to the lower digit side, and the number of shifts C (C is 1
When the above integer is 0, the lower 8 bits of the ignition count value calculated by the ignition position calculation means are used as the count value of the second counter as it is. The lower 8 bits of the count value
A second counter count value setting means for setting the count value of the counter, a frequency division ratio setting means for setting the frequency division ratio to 1 / (2 ^c ), and a reference clock signal when a reference rotation angle position is detected. Second counter control means for performing a count operation of the count value set in the second counter at a frequency obtained by dividing the frequency by the set frequency division ratio, wherein the count operation of the second counter is performed. It is configured to generate an ignition signal when completed.

When an 8-bit RAM is used as the RAM of the microcomputer, the upper 8 bits and the lower 8 bits of the rotation speed measurement count value are stored in the first and second rotation speed storage memories, respectively. The upper 8 bits and lower 8 bits of the ignition count value are respectively assigned to the first and second bits.
In the memory for storing the ignition position.

In this case, the ignition signal generating means determines whether the content of the first ignition position storage memory is 0 or 1 or more, and when it is determined that the content of the memory is 1 or more. Count value shifting means for shifting each digit of a binary number stored in each of the first and second ignition position storage memories to a lower digit side until the contents of the first ignition position storage memory become zero. And when the number of shifts C (C is a positive integer including 0) by the count value shift means is 0, the second ignition position storage storing the lower 8 bits of the ignition count value calculated by the ignition position calculation means. The content of the second memory is used as it is as the count value of the second counter, and when the number of shifts C is 1 or more, the content stored in the second ignition position storage memory after the shift is used as the count value of the second counter. The second power to set A pointer count setting means, the frequency division ratio 1
/ (2 ^c ), a dividing ratio setting means for setting the reference clock frequency to a frequency obtained by dividing the reference clock frequency by the set dividing ratio when the reference rotation angle position is detected, and a counter set in the second counter. It can be constituted by second counter control means for performing a numerical value counting operation.

In the case where a down counter is used as the first counter and the second counter, the rotation speed storage means stores the first counter.
Immediately before the counter is cleared, 1 is added to the binary number obtained by inverting each digit of the lower 8 bits of the count value of the first counter to obtain the lower 8 bits of the count value for measuring the rotational speed.
Configure to get bits.

According to the present invention, there is provided a rotational speed judging means for judging whether or not the rotational speed of the engine exceeds a set value. The counting operation of the second counter is permitted and the second
When the counting operation of the counter is completed, an ignition signal is generated, and when it is determined that the rotation speed is equal to or less than the set value, the counting operation of the second counter is prohibited and the fixed ignition position is detected by the fixed ignition position signal. It is preferable that the ignition signal generating means further include an ignition signal switching means for generating an ignition signal when the ignition signal is generated.

[0019]

With the above arrangement, the number of revolutions and the ignition position are determined by using two 8-bit counters.
Since the processing can be carried out in base numbers, the ignition position of the internal combustion engine can be accurately controlled using an inexpensive microcomputer having two 8-bit counters.

[0020]

FIG. 1 shows a hardware configuration of an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an ignition circuit which generates a high voltage for ignition when an ignition signal is given. This ignition circuit is well known as a capacitor discharge type circuit, and includes an ignition coil 2 having a primary coil 2a and a secondary coil 2b, and an exciter provided in a magnet generator mounted on an output shaft of an internal combustion engine (not shown). Coil 3, ignition energy storage capacitor 4, discharge thyristor 5
And diodes 6 and 7. More specifically, one end of the primary coil 2a of the ignition coil is grounded together with one end of the exciter coil 3, and the other end of the primary coil 2a is connected to one end of the secondary coil 2b. One end of the capacitor 4 is also connected to the other end of the primary coil 2a,
The other end of the capacitor 4 is connected to the other end of the exciter coil 3 through a diode 6 whose cathode faces the capacitor. The anode of the thyristor 5 is connected to the connection point between the capacitor 4 and the diode 6, and the cathode of the thyristor is grounded. A diode 7 is connected to both ends of the primary coil 2a of the ignition coil with the cathode facing the ground. The other end of the secondary coil 2b of the ignition coil is connected to a non-ground side terminal of a spark plug 8 attached to a cylinder of an engine (not shown).

In the above-mentioned ignition circuit 1, the exciter coil 3 induces an AC voltage Ve in synchronization with the rotation of the engine. When the exciter coil 3 generates the AC voltage Ve of the positive half cycle in the direction of the arrow shown in the figure, the exciter coil 3
→ Diode 6 → Capacitor 4 → Diode 7 and primary coil 2 a → Capacitor 4 in the path of exciter coil 3
Is charged to the illustrated polarity. When the ignition signal Vi is applied to the gate of the thyristor 5, the thyristor 5 conducts, and the electric charge of the capacitor 4 is discharged to the primary coil 2a of the ignition coil through the thyristor 5. This discharge induces a high voltage for ignition in the secondary coil 2b of the ignition coil,
The high voltage is applied to the spark plug 8. As a result, a spark is generated in the ignition plug 8, and the engine is ignited.

Reference numeral 10 denotes a microcomputer, which is composed of an MPU (not shown),
An OM 10a and a RAM 10b, an 8-bit first counter 10e provided with a 6-bit first prescaler 10d at the preceding stage, and an 8-bit second counter 10g provided with a 6-bit second prescaler 10f at the preceding stage. And a clock circuit 10h that supplies a clock pulse to the counter,
It consists of a one-chip microcomputer built into a chip.
In this example, both the first counter 10e and the second counter 10g are 8-bit down counters, and the count values counted by these counters are 00H to FF.
H (where H indicates hexadecimal notation) can be appropriately set on software.

The clock circuit 10h comprises an oscillating circuit for generating a reference clock pulse Vp at a period of 1 μsec. The reference clock pulse is supplied to first and second counters 10e and 10e through prescalers 10d and 10f.
g.

The prescalers 10d and 10f divide the frequency of the reference clock pulse Vp by a set division ratio n (n is an integer of 1 or more), and the divided clock pulses are sent to the counters 10e and 10g. give.

In this embodiment, the frequency division ratio of the prescaler 10d is set to 1, and the count value of the first counter 10e is F
FH is set. Therefore, the first counter 10e has:
A clock pulse having the same frequency as the reference clock pulse Vp is provided. The first counter 10e is cleared when the interrupt signal INT1 is given at the reference position and starts counting operation, and starts counting at 00H, FFH, FEH, FDH,
…, The counting operation of 03H, 02H, 01H is repeated,
Each time the count value becomes 01H (every time the count operation is completed), an interrupt signal INT2 is sent to the interrupt control circuit 10c.
give.

The frequency division ratio of the prescaler 10f is appropriately set on software in accordance with the number of bits of the count value for measuring the ignition position.
A clock pulse having a frequency obtained by dividing the frequency of the reference clock pulse Vp by the set dividing ratio is supplied to the second counter 10.
Give to g. The second counter 10g counts down the count value set on the software, and when the counting is completed (when the count value becomes 01H), the second counter 10g supplies an interrupt signal INT3 to the interrupt control circuit 10c.

Numeral 11 denotes a signal coil provided on a signal generator (pulsar) mounted on the output shaft of the internal combustion engine. This signal coil, as shown in FIG. A first signal Vs1 that exceeds a threshold level at a reference position θ1 set at a position advanced from the fixed ignition position (usually a maximum advance position), and a threshold signal that exceeds a threshold level at a fixed ignition position θ2. The second signal Vs2 is generated once per revolution of the engine. The fixed ignition position is an ignition position at a low speed of the engine. This fixed ignition position may be set to be equal to the minimum advance position of the engine, and a position advanced from the minimum advance position (the ignition position at a low engine speed). (Appropriate position).

In the illustrated example, the first signal Vs1 is composed of a pulse of negative polarity, and the second signal Vs2 is composed of a pulse of positive polarity. The output of the signal coil 11 is a waveform shaping circuit 12
Has been entered. The waveform shaping circuit 12 includes the signal coil 11
The waveform shaping circuit converts the first signal Vs1 and the second signal Vs2 into a pulse waveform reference signal P1 (FIG. 7B) and a fixed ignition position signal P2 (FIG. 7C). ). The waveform shaping circuit 12 also outputs a signal P2 'corresponding to a signal obtained by inverting the fixed ignition position signal P2, and outputs the reference signal P1 and the fixed ignition position signal P2 output by the waveform shaping circuit 12.
The signal P2 'obtained by inverting the fixed ignition position signal is input to the interrupt control circuit 10c through the input port of the microcomputer 10. Microcomputer 1
0 recognizes the falling of the input signal from the high level to the low level, and the falling of the reference signal P1 generated at the reference rotation angle position θ1 is recognized as the interrupt signal INT1. Also, the falling of the fixed ignition position signal P2 is recognized as an interrupt signal INT4, and the falling of the signal P2 'generated at the fixed ignition position θ2 (rising of the fixed ignition position signal P2) is recognized as an interrupt signal INT5. I have.

Output port A of microcomputer 10
Is connected to the base of a PNP transistor 15 through a resistor 14, and the emitter of the transistor 15 is connected to a power supply line E connected to a DC power supply circuit output terminal (not shown). A resistor 16 is connected between the emitter and the base of the transistor 15, and the collector of the transistor 15 is connected to the resistor 1
7 and the diode 18 are connected to the gate of the discharging thyristor 5.

In this example, an ignition signal output circuit 19 is constituted by the resistors 14, 16, and 17, the transistor 15, and the diode 18. When the microcomputer 10 outputs the ignition position detection signal Vf, the ignition signal is output. An ignition signal Vi is supplied from the circuit 19 to the ignition circuit 1.

The microcomputer 10 operates by being supplied with a power supply voltage from a DC power supply (not shown). As this DC power supply, a power supply circuit that rectifies the output of a magnet generator attached to the engine to generate a DC voltage, or a power supply circuit that rectifies the output of the magnet generator to generate a DC voltage, and a battery It is preferable to use a combination of the above. If the microcomputer is configured to operate with a power supply that generates a DC voltage using a magnet generator attached to the engine as a power supply, the present invention can be applied to an internal combustion engine that drives a vehicle or the like without a battery.

When the microcomputer is driven only by the battery, if the battery is over-discharged, the microcomputer cannot be operated and the engine cannot be operated. If the battery is over-discharged at sea, it may not be possible to return to the port.However, if the microcomputer can be operated using a magnet generator attached to the engine as a power supply, such a problem can be solved. Can be prevented.

The microcomputer 10 calculates the engine speed [rpm] by executing a program stored in the ROM, and calculates an ignition position for the engine speed. The microcomputer 10 also determines whether or not the rotation speed exceeds a set value, measures the ignition position calculated when the rotation speed exceeds the set value, and determines whether the rotation angle of the engine is equal to the ignition position. Is detected, the potential of the output port A is changed from a high level state to a low level (ground potential) state. The decrease in the potential of the output port A is used as the ignition command signal Vf. When the rotation speed is equal to or less than the set value, the fixed ignition position θ is not measured without measuring the ignition position.
In step 2, when the interrupt signal INT5 is generated, the potential of the output port A is lowered to generate the ignition command signal Vf.

When the ignition command signal Vf is generated (when the potential of the output port A decreases), the transistor 15 is turned on.
The ignition signal Vi is given to the discharge thyristor 5 of the ignition circuit 1 through the resistor 17, the resistor 17 and the diode 18.

FIGS. 2 to 6 are flowcharts showing the algorithm of the program executed by the microcomputer 10. FIG. FIG. 2 shows a main routine started when a power supply voltage is applied to the microcomputer 10, and FIG. 3 shows an interrupt routine executed when an interrupt signal INT1 is generated. FIG. 4 shows an interrupt routine executed when the interrupt signal INT2 is generated, and FIGS. 5 and 6 show an interrupt routine executed when the interrupt signals INT3 and INT4 are generated, respectively.

When a power supply voltage is applied to the microcomputer 10, a main routine shown in FIG. 2 is started.
In this main routine, first, each unit is initialized (initialized), and the first rotation speed storage memory NRPM is initialized.
The engine rotation speed is calculated from the rotation speed measurement count values stored in the first and second rotation speed storage memories NRPM2, respectively, and the calculated rotation speed is stored at a predetermined address in the RAM.

First and second rotational speed memory NRP
M1 and NRPM2 are assigned predetermined addresses of the RAM, and these memories NRPM1 and NRPM2
Each has a first counter 1 during one revolution of the engine.
The upper 8 bits and lower 8 bits of the number of clock pulses (16-bit binary number) counted by 0e are stored. The process of storing the rotational speed measurement count value in the memories NRPM1 and NRPM2 will be described later.

After calculating the rotation speed, the ignition position at the calculated rotation speed is calculated using a map giving the relationship between the rotation speed and the ignition position. The map used for this calculation is
Each bending point of a characteristic (generally represented by a line graph) giving a relationship between the rotation speed and the ignition position is set as a map point, and the rotation speed and the ignition position at each map point are stored in the form of a table. The ignition position is calculated by interpolation using this map.

Next, the number of reference clock pulses to be counted while the engine rotates from the reference rotation angle position to the rotation angle position corresponding to the calculated ignition position is defined as the ignition count value, and this ignition count value is set to 16 The arithmetic operation is performed using a binary number of bits, and the upper 8 bits and lower 8 bits of the counted value are stored in first and second ignition position storage memories IGTIME1 and IGTIME2 respectively assigned to predetermined addresses of the RAM 10b.

Next, the number of shifts C is set to 0, and it is determined whether or not the upper 8 bits of the ignition count value stored in the first ignition position storage memory IGTIME1 are 0.
As a result, the first ignition position storage memory IGTIME1
If the upper 8 bits of the ignition count stored in the microcomputer are 1 or more, 0 is set in the carry flag CY provided in the microcomputer, and then the ignition position storage memory I
While moving the last one bit of the upper 8 bits and the lower 8 bits of the ignition count value stored in GTIME1 and IGTIME2 to the carry flag CY,
"0" stored in the carry flag CY is moved to the most significant digit of the upper 8 bits and lower 8 bits of the ignition count value. Thereby, IGTIME1 and IGTIME2
, The upper 8 bits and the lower 8 bits of the ignition count value respectively stored are shifted by one bit to the lower digit side. Next, after increasing the number of shifts C by one, the process returns to the step of determining whether or not the upper 8 bits of the ignition count value stored in the first ignition position storage memory IGTIME1 have become 0. If the upper 8 bits of the use count value are not 0, the process of shifting the upper 8 bits and lower 8 bits stored in IGTIME1 and IGTIME2 one bit at a time toward the lower digit is repeated. By these processes, each digit of the ignition count is shifted to the lower digit until the upper 8 bits of the ignition count become zero. Each time each digit of the ignition count value shifts to the lower digit side once, the magnitude of the ignition count value becomes １ ／. For example, if the shift is performed twice before the upper 8 bits of the ignition count value becomes zero, the shifted ignition count value becomes 1/4 of the calculated value, and the shift is performed three times. If you do
The value of the ignition count value after the shift is 1/8 of the calculated value.

First ignition position storage memory IGTIME
As a result of determining whether or not the upper 8 bits of the ignition count value stored in 1 are 0, if it is determined that the upper 8 bits are 0, the frequency division ratio of 1 / f in the prescaler 10f is 1/0.
2 ^c (C is a positive integer including 0) is stored in the memory I for storing the frequency division ratio.
Store in GPRE. Next, the ignition position memory I
The lower 8 bits of the ignition count value stored in GTIME2 are stored in ignition count value storage memory IGTIME, and the process returns to the step of obtaining the rotational speed. In the present invention, the shifted ignition count value stored in the memory IGTEM is set in the second counter 10g, and the counter 10
Let g perform a counting operation. If the shift has been performed C times,
Although the shifted ignition count value counted by the second counter 10g is 1 / ^2c of the ignition count value calculated as the reference clock pulse count value, in the present invention, the second counter In order for 10g to count pulses of a frequency obtained by dividing the frequency of the reference clock pulse by 1 / ^2c ,
The measurement of the ignition position can be performed without any trouble.

As described above, the first counter 10e
The reference clock pulse Vp is counted, and 00H, FFH,
... Repeats the down count of 01H, and the count value becomes 01H
, An interrupt signal INT2 is generated. When the interrupt signal INT2 is generated, the interrupt routine shown in FIG. 4 is executed. In this interrupt routine, the contents of the carry bit storage memory REVRAM assigned to a predetermined address of the RAM are incremented (REVR).
AM is incremented by 1), and it is determined whether or not the REVRAM overflows. If the REVRAM has not overflown, the program returns to the main routine. If the REVRAM has overflown, the overflow determination flag OVE appears.
RFL is set to 1 and the process returns to the main routine.

The signal generator 13 generates a reference signal,
When the microcomputer 10 receives the interrupt signal INT1, the interrupt routine shown in FIG. 3 is executed.
In this interrupt routine, first, the second counter 10g
Is set to the ignition count stored in the ignition count storage memory IGTIME, and the frequency division ratio storage memory IGPR is set.
The frequency division ratio stored in E is set in the second prescaler 10f. Next, an overflow determination flag OVERFL
Is determined to be 1 or not. When OVERFL is not 1 (in the case of 0), the carry bit storage memory REV
The contents of the RAM are stored in the first rotation speed storage memory NRPM1 as the upper 8 bits of the rotation speed measurement count value, and the exclusive OR of the count value of the first counter 10e and FFH is set to 1 (exclusive OR). Is stored in the second rotational speed storage memory NRPM2 as the lower 8 bits of the rotational speed measurement count value. The operation of adding 1 to the exclusive OR (exclusive OR) of the count value of the first counter 10e and FFH adds 1 to the binary number obtained by inverting each digit of the count value of the first counter 10e. Operation. By performing such an operation, the count value of the down-count can be converted into the count value of the up-count.

When the overflow determination flag OVERFL is not 1 (the carry bit storage memory REVRAM)
Is not overflowed), the upper 8 bits and lower 8 bits of the rotation speed measurement count value are stored in the first and second rotation speed storage memories NRPM1 and NRPM2 as described above. Then, the carry bit storage memory REVRAM is cleared, the first counter 10e is cleared, and the counting operation of the first counter is started.

If it is determined that the overflow determination flag OVERFL is 1, the flag OVERFL is determined.
Is set to 0, the first and second rotational speed storage memories NR
FFH (the maximum value of the count value of the second counter) is inserted into both PM1 and NRPM2 to maximize the count value for measuring the number of revolutions, and then the carry bit storage memory REVRAM and the first counter 10e are cleared. , The counting operation of the first counter is started.

After clearing the carry bit storage memory REVRAM and the first counter 10e, the first and second
The rotation speeds stored in the rotation speed storage memories NRPM1 and NRPM2 are set values (in this example, 1000 [rpm]
m]), and if the rotation speed exceeds the set value, the interruption by the interruption signal INT5 is prohibited, and the counting operation of the second counter 10g is permitted. Return to routine. If the rotation speed is equal to or less than the set value, the interruption by the interruption signal INT5 is permitted, the counting operation of the second counter 10g is inhibited, and the process returns to the main routine.

If the rotation speed exceeds the set value, the counting operation of the second counter 10g is started when the operation of the second counter 10g is permitted. The counting operation of the second counter 10g is actually started because the reference signal is generated and the interrupt signal INT1 is generated, then the count value is set in the second counter, and the frequency is divided into the second prescaler. Set ratio, memory for storing rotation speed NRPM1, NR
Transfer of count value to PM2, memory R for carry bit storage
After various processes such as clearing of the EVRAM are performed, since these processes are performed in a very short time,
It can be considered that the counting operation of the second counter 10g is started when the reference signal is generated. The second counter 10g generates an interrupt signal INT3 when the operation of counting the set count value is completed. When the interrupt signal INT3 is generated, the interrupt control circuit 10c executes the interrupt routine shown in FIG. 5 to set the potential of the port A to a low level (the logic of the binary signal is "0"). The decrease in the potential of the port A becomes the ignition command signal Vf. When the ignition command signal Vf is generated, the transistor 15
Is turned on to give an ignition signal Vi to the discharge thyristor 5, so that an ignition operation is performed. When the interrupt signal INT4 is generated at a position slightly delayed from the fixed ignition position θ2,
The interrupt routine shown in FIG. 6 is executed, the potential of the port A of the microcomputer 10 is set to a high level (the logic of the binary signal is "1"), and the ignition command signal is extinguished. As a result, the transistor 15 is turned off, and the supply of the ignition signal Vi to the discharge thyristor 5 is stopped.

When the number of revolutions is equal to or less than the set value, the second counter 1
0g is prohibited and the interrupt by the interrupt signal INT5 is permitted. When the interrupt signal INT5 is generated at the fixed ignition position θ2, the potential of the port A is set to a low level. The thyristor 5 is provided with an ignition signal. This ignition signal is extinguished when the interrupt signal INT4 is generated. That is,
When the engine speed is lower than the set value, an ignition signal is always generated at the fixed ignition position, and the ignition position is fixed at the fixed ignition position.

In the above embodiment, the counter clear means is realized by the process of clearing the first counter in the interrupt routine shown in FIG. 3, and the total counting operation of the first counter is performed by the interrupt routine shown in FIG. Each time is completed, the contents stored in the carry bit storage memory are incremented by one.
Thus, a carry storage means for increasing the number by one is realized. FIG.
In the interrupt routine shown in FIG.
Transferring the contents of the memory REVRAM to the memory;
The process of inverting each digit of the count value of the counter and adding 1 to the memory NRPM2 and storing the value in the memory NRPM2 realizes the rotation speed storage means. Further, in the main routine of FIG. 2, the count value shifting means is realized by a process of shifting each digit of the storage contents of IGTIME1 and IGTIME2, a process of storing the frequency division ratio in IGPRE in the main routine, and an interrupt of FIG. Second in routine
By transferring the contents of the IGPRE to the prescaler 10f, the frequency division ratio setting means is realized. In addition, in the interrupt routine of FIG.
In the process of transferring to the TIME and in the interrupt routine of FIG. 3, the process of transferring the contents of the IGTIME to the second counter 10g implements a second counter count value setting means. In the interrupt routine shown in FIG. The second counter control means is realized by the process of permitting the counting operation of the second counter.

In the interrupt routine shown in FIG. 3, a process for determining whether or not the rotational speed exceeds a set value implements a rotational speed determining means.
In the process of permitting or inhibiting the operation of the counter of the above, the ignition signal switching means is realized.

In the above embodiment, the down counter is used as the first and second counters 10e and 10g.
Up counters can be used as these counters. When an up counter is used as the first counter 10e, a reference signal is generated and an interrupt signal IN is generated.
When T1 occurs, the count value of the first counter 10e may be transferred to the NRPM2 as the lower 8 bits as it is.

In the above embodiment, the microcomputer 10 generates an ignition signal at the fixed ignition position when the rotation speed is equal to or lower than the set value (at an extremely low speed).
The fixed ignition position signal P2 may be used as an ignition signal at an extremely low speed, and the fixed ignition position signal P2 and the ignition signal Vi given from the microcomputer may be supplied to the ignition circuit through an OR circuit.

In the above embodiment, a capacitor discharge type circuit for charging an ignition energy storage capacitor with an exciter coil is used as the ignition circuit 1. However, a DC-DC converter using a battery as a power source without using an exciter coil is used. The present invention can be applied to a case where a capacitor discharge type ignition circuit in which a capacitor for storing ignition energy is charged by a (boost circuit) is used. The ignition circuit may be any circuit that generates a high voltage for ignition when an ignition signal is given, and may be used even when a current interruption type ignition circuit is used instead of the capacitor discharge type ignition circuit. Of course, the invention can be applied.

In the above embodiment, a signal generator having a signal coil is used as a signal source of the signal generating device. However, a signal is generated by detecting a change in magnetic flux using a magnetic detecting element such as a Hall element. A signal generator can also be used.

[0055]

As described above, according to the present invention, the number of revolutions and the ignition position are set to 1 by using two 8-bit counters.
Since the processing can be performed with a 6-bit binary number, there is an advantage that the ignition position of the internal combustion engine can be accurately controlled by using an inexpensive microcomputer having two 8-bit counters.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a hardware configuration according to an embodiment of the present invention.

FIG. 2 is a flowchart showing an algorithm of a main routine executed in the embodiment of the present invention.

FIG. 3 is a flowchart showing an algorithm of an interrupt routine executed when a reference signal is generated in the embodiment of the present invention.

FIG. 4 is a flowchart showing an algorithm of an interrupt routine executed each time the first counter completes a counting operation in the embodiment of the present invention.

FIG. 5 is a flowchart showing an algorithm of an interrupt routine executed each time the second counter completes a counting operation in the embodiment of the present invention.

FIG. 6 is a flowchart showing an algorithm of an interrupt routine executed each time a fixed ignition position signal is generated in the embodiment of the present invention.

FIG. 7 is a waveform diagram showing signal waveforms of respective units according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ignition circuit 2 Ignition coil 3 Exciter coil 4 Ignition energy storage capacitor 5 Thyristor for discharge 10 Microcomputer 13 Signal generator

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-55-25595 (JP, A) JP-A-54-22742 (JP, A) JP-A-3-264773 (JP, A) (58) Field (Int. Cl. ⁷ , DB name) F02P 5/15 F02D 45/00 372

Claims (4)

(57) [Claims] An ignition circuit for generating a high voltage for ignition when an ignition signal is applied, a microcomputer,
A signal generator for generating at least a fixed ignition position signal for detecting a fixed ignition position of an internal combustion engine and a reference signal for detecting a reference rotation angle position set at a position advanced from the fixed ignition position Rotation speed measuring means for counting a reference clock pulse generated during one rotation of the internal combustion engine to obtain a rotation speed measurement count value consisting of a 16-bit binary number, and an internal combustion engine based on the reference rotation angle position. An ignition position calculating means for calculating the number of clock pulses to be counted while the engine is rotating to the ignition position as an ignition count value consisting of a 16-bit binary number for each rotation speed; An ignition signal generating means for counting and generating the ignition signal is realized by the microcomputer, and the ignition device for the internal combustion engine controls the ignition position of the internal combustion engine with respect to the rotation speed. Thus, the microcomputer has an 8-bit first counter that performs a counting operation at a predetermined reference clock frequency, and an 8-bit first counter that performs a counting operation at a frequency obtained by dividing the reference clock frequency by a predetermined division ratio. A counter clearing means for clearing the first counter each time a reference rotation angle position is detected by the reference signal; and a RAM provided in the microcomputer. A carry storage unit for increasing a storage content of the carry bit storage memory by one each time the first counter completes a total counting operation using a predetermined address as a carry bit storage memory; The upper 8 bits of the rotational speed measurement count value obtained from the storage content of the carry storage unit immediately before the counter is cleared, and Rotation speed storage means for storing the lower 8 bits of the rotation speed measurement count value obtained from the count value of the first counter immediately before the counter is cleared. It is determined whether the upper 8 bits of the 16-bit ignition count calculated by the ignition position calculator are 0 or 1 or more, and it is determined that the upper 8 bits of the ignition count are 1 or more. Sometimes, the count value shifting means for shifting each digit of the ignition count value to the lower digit side until the upper 8 bits of the ignition count value becomes 0, and the number of shifts C (C is When a positive integer including 0) is 0, the lower 8 bits of the ignition count value calculated by the ignition position calculation means are used as the count value of the second counter as it is, and when the number of shifts C is 1 or more, the shift is performed. rear A second counter count value setting means for setting the lower 8 bits of the ignition count value as a count value of the second counter, and a frequency division ratio setting means for setting the frequency division ratio to 1 / (2 ^c ). A second counter control means for performing a counting operation of the count value set in the second counter at a frequency obtained by dividing the reference clock frequency by the set dividing ratio when the reference rotation angle position is detected. And an ignition device for an internal combustion engine configured to generate the ignition signal when the counting operation of the second counter is completed. 2. An ignition circuit for generating a high voltage for ignition when an ignition signal is applied, a microcomputer,
A signal generator for generating at least a fixed ignition position signal for detecting a fixed ignition position of an internal combustion engine and a reference signal for detecting a reference rotation angle position set at a position advanced from the fixed ignition position Rotation speed measuring means for counting a reference clock pulse generated during one rotation of the internal combustion engine to obtain a rotation speed measurement count value consisting of a 16-bit binary number, and an internal combustion engine based on the reference rotation angle position. The upper 8 bits of the ignition count value calculated by calculating the number of clock pulses to be counted while the engine rotates to the ignition position as a 16-bit binary count value for each rotation speed And an ignition position calculating means for storing the lower 8 bits in first and second ignition position storage memories, respectively, and an ignition signal generator for counting the ignition count value and generating the ignition signal. Is realized by the microcomputer, and the ignition position of the internal combustion engine is controlled with respect to the number of revolutions of the internal combustion engine, wherein the microcomputer performs a counting operation at a predetermined reference clock frequency. 1 counter, and an 8-bit second counter that performs a counting operation at a frequency obtained by dividing the reference clock frequency by a predetermined frequency division ratio, wherein the rotation speed measurement unit uses a reference rotation angle based on the reference signal. A counter clear means for clearing the first counter each time a position is detected; and a total counting operation of the first counter using a predetermined address of a RAM provided in the microcomputer as a carry bit storage memory. Carry storage means for increasing the storage contents of the carry bit storage memory by one each time the completion is completed; The upper 8 bits of the rotation speed measurement count value obtained from the storage content of the carry storage unit immediately before the execution and the lower 8 bits of the rotation speed measurement count value obtained from the count value of the first counter To the first and second
The ignition signal generating means determines whether the content of the first ignition position storage memory is 0 or 1 or more. When it is determined that the content of the memory is 1 or more, each of the binary numbers stored in the first and second ignition position storage memories until the content of the first ignition position storage memory becomes 0. A count value shifting means for shifting the digit to the lower digit side, and the number of shifts C (C is a positive integer including 0) is 0
In this case, the content of the second ignition position storage memory storing the lower 8 bits of the ignition count value calculated by the ignition position calculation means is used as it is as the count value of the second counter, and the number of shifts C is 1 or more. In the case of, the second counter count value setting means for setting the content stored in the second ignition position storage memory as the count value of the second counter after the shift, and setting the frequency division ratio to 1 / (2 ^c ), And counting the count value set in the second counter at a frequency obtained by dividing the reference clock frequency by the set division ratio when the reference rotation angle position is detected. An ignition device for an internal combustion engine, comprising: second counter control means for performing an operation, wherein the ignition signal is generated when the counting operation of the second counter is completed. 3. The first counter and the second counter comprise a down counter, and the rotation speed storage means stores the lower 8 bits of a count value of the first counter immediately before the first counter is cleared. The ignition device for an internal combustion engine according to claim 1 or 2, wherein the lower 8 bits of the rotation speed measurement count value are obtained by adding 1 to a binary number obtained by inverting each digit of the internal combustion engine. 4. The engine according to claim 1, wherein the ignition signal generating means determines whether the engine speed exceeds a set value, and determines whether the engine speed exceeds the set value. When it is determined, the counting operation of the second counter is permitted, and when the counting operation of the second counter is completed, an ignition signal is generated. When it is determined that the rotation speed is equal to or less than the set value, the second operation is performed. 2. An ignition signal switching means for inhibiting the counting operation of the second counter and generating an ignition signal when a fixed ignition position is detected by the fixed ignition position signal. Or the ignition device for an internal combustion engine according to any of 3.