JP3329165B2 - 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 an ignition position using a microcomputer.

[0002]

2. Description of the Related Art In recent years, various demands have been made on an internal combustion engine, such as purification of exhaust gas, improvement of fuel consumption, reduction of noise, and improvement of output power. 2. Description of the Related Art Digitally controlled ignition devices that precisely control the ignition position of an internal combustion engine using a microcomputer have come to be widely used.

An ignition device for an internal combustion engine that controls an ignition position by using a microcomputer includes, for example, an ignition circuit that controls a primary current of an ignition coil to generate a high voltage for ignition when an ignition signal is given. A reference position set at a rotation angle position advanced in phase from the top dead center of the internal combustion engine (a rotation angle position of the crankshaft corresponding to the piston top dead center) and a rotation angle delayed in phase from the reference position A signal generator for generating a reference signal and a fixed ignition position signal at each position, a rotation speed detecting means for detecting a rotation speed of the engine from a generation cycle of an output of the signal generator, and an ignition position at the detected rotation speed Ignition position calculating means for calculating
An ignition command signal generating means for starting measurement of the calculated ignition position when the reference signal is generated, generating an ignition command signal when the calculated ignition position is measured, and generating an ignition command signal Or an ignition signal output circuit that supplies an ignition signal to the ignition circuit when the fixed ignition position signal is generated.

[0004] The ignition position calculation means calculates the ignition position at each rotational speed in the form of the time required for the engine to rotate from the reference position to the ignition position. The ignition command signal generating means starts measuring the calculated ignition position when it is detected that the reference signal has been generated, and generates an ignition command signal when the measurement is completed. The fixed ignition position signal generated by the signal generator is used when the engine is running at extremely low speed (idling).
The ignition position is usually set in the range of 5 ° to 13 ° before the top dead center of the engine.

[0005] In this specification, the term "position" in the context of an ignition position, a signal generation position, or the like means a rotation angle position of an output shaft (usually a crankshaft) of an engine, and is actually expressed by a rotation angle. You.

In both the two-stroke engine and the four-stroke engine, if the compression ratio is high, the piston may be pushed back at the time of starting and the engine may rotate in the reverse direction. This phenomenon is commonly called Ketchin, and its causes are as follows.

(A) There is no momentum in the rotation of the crankshaft at the time of starting because the operating force when the driver performs the starting operation is insufficient or the voltage of the battery for driving the starter motor is low. Sometimes, before the piston reaches the ignition position set before the top dead center, the piston is pushed back due to an increase in the internal pressure of the cylinder, and the engine reverses.

(B) Ignition is performed at the ignition position before top dead center in a state where the rotation of the crankshaft at the time of starting the engine has no momentum, and the piston is pushed back by the pressure of the explosion generated at that time, and the engine is started. Reverse.

The reversal caused by the cause (a) is not due to the explosion of the fuel, so that a large force does not act on the starting device of the engine at the time of the reversal, so that no major problem occurs. However, after the piston is pushed back by the pressure in the cylinder and reverse rotation occurs, if the ignition operation is performed in the process of the reverse rotation, the reverse rotation of the engine may be maintained.

[0010] The reverse rotation caused by the cause (b) is due to the explosion of fuel, so that a large force acts on the starting device at the time of the reverse rotation. When such a reverse rotation occurs, there is a possibility that the driver may be harmed if the starting device uses a human power such as a kick starter or a rope starter. When the starter is an electric starter, a large force is applied to the gear mechanism that couples the starter motor and the crankshaft during reverse rotation, and the gear mechanism may be damaged.

[0011]

As one method for preventing reverse rotation of the engine, it is conceivable to set the ignition position at an extremely low speed of the engine (during start-up and idling) to a position delayed from the top dead center. Can be For this purpose, for example, the position where the signal generator generates the fixed ignition position signal is set to a position that is later than the top dead center, and when the rotation speed of the engine is lower than the set rotation speed (at extremely low speed). However, if the ignition position is delayed from the top dead center of the engine even during the idling operation, the rotation of the engine cannot be stably maintained. In order to stably perform the idling operation, it is necessary to set the ignition position to an appropriate position within a range of 5 ° to 13 ° before the top dead center.

Therefore, the position where the signal generator generates the fixed ignition position signal is delayed from the top dead center so that the ignition operation is performed using the fixed ignition position signal as the ignition signal when the engine is started, and after the engine is started. The microcomputer calculates the ignition position when idling on software,
It is conceivable to generate an ignition signal at the calculated ignition position.

In this case, the microcomputer calculates the ignition position at each rotational speed in the form of the time required for the crankshaft to rotate from the reference position to the ignition position. When the signal generator generates the reference signal, the microcomputer calculates the ignition position. The measurement of the ignition position is started, and an ignition signal is generated when the measurement is completed. When the rotational speed of the crankshaft of the engine during idling is stable enough to be considered constant, the ignition position during idling can be kept constant by such a method, and the rotation of the engine can be stabilized. .

However, when the engine is idling, the rotation speed at each rotation angle position of the crankshaft fluctuates under the influence of the pressure change in the cylinder, and the degree of the fluctuation is not constant. If the measurement of the ignition position calculated from the position where the reference signal is generated is started, the ignition position fluctuates for each rotation, and it becomes difficult to stabilize the rotation during idling.

In order to stabilize the rotation during idling, the ignition position must be determined by the signal generator at a position where the fixed ignition position signal is generated, instead of being determined by calculation. Then, as described above, it is unavoidable that the engine may be reversed at the time of starting.

An object of the present invention is to provide an ignition device for an internal combustion engine that can reliably prevent reverse rotation of the engine and stably perform idling operation.

[0017]

According to the present invention, a signal generator includes a reference position having a phase advanced from a top dead center of an engine;
The reference signal and the fixed ignition position signal are respectively generated at the fixed ignition position where the phase is delayed from the reference position and the phase is advanced from the top dead center, so that the rotation speed of the internal combustion engine becomes equal to or less than the set rotation speed. When it is in the state (at extremely low speed), an ignition signal is generated at the fixed ignition position. With this configuration, the ignition position during idling operation can be fixed at a fixed position before top dead center (usually set in the range of 5 ° to 13 ° before top dead center). Can be performed stably.

Further, in the present invention, when the rotational speed of the engine is equal to or lower than the set rotational speed, the time Tn required from the time when the signal generator generates the reference signal to the time when the fixed ignition position signal is generated is measured. And the time Tn is equal to the allowable upper limit T
If the time exceeds ns, the engine is likely to reverse (there is not enough momentum to rotate the crankshaft).
Misfire the engine by prohibiting the generation of ignition signals,
Only when the measured time Tn is less than the allowable upper limit value Tns, the ignition signal is generated at the position where the fixed ignition position signal is generated.

With this configuration, if the crankshaft has no momentum at the time of starting and there is a possibility that the engine will reverse if the ignition operation is performed as it is, the engine is misfired,
Since the engine is ignited only when there is momentum in the rotation of the crankshaft and there is no risk of the engine reversing, it is possible to eliminate the possibility of the engine reversing at startup.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An ignition device for an internal combustion engine according to the present invention controls an primary current of an ignition coil to generate a high voltage for ignition when an ignition signal is given, and an ignition circuit.
The reference signal is set at a reference position set at a position where the phase is advanced from the top dead center of the internal combustion engine, and at a fixed ignition position set at a position where the phase is delayed from the reference position and advanced from the top dead center. A signal generator for generating a fixed ignition position signal, a rotation speed detection means for detecting a rotation speed of the internal combustion engine from a generation cycle of the reference signal, and a rotation speed of the internal combustion engine with respect to the rotation speed detected by the rotation speed detection means. Ignition position calculating means for calculating an ignition position; rotation speed determining means for determining whether or not the rotation speed detected by the rotation speed detection means is equal to or lower than a set rotation speed; A normal operation time ignition command signal generating means for generating an ignition command signal at the ignition position calculated by the ignition position calculation means when it is determined that the speed is exceeded; An extremely low-speed ignition control timing means for measuring the time required for the engine to rotate from the reference signal generation position to the fixed ignition position signal generation position when the rotation speed is determined to be equal to or lower than the set rotation speed, When it is determined that the rotation speed is equal to or less than the set rotation speed and the time measured by the timing means is determined to be equal to or less than the allowable upper limit, an ignition command signal is generated at the position where the fixed ignition position signal is generated, and the rotation is performed. An extremely low-speed ignition command signal generating means for stopping the generation of the ignition command signal when it is determined that the speed is equal to or less than the set rotation speed and it is determined that the time measured by the timing means exceeds the allowable upper limit value; And an ignition signal output circuit that supplies an ignition signal to the ignition circuit when an ignition command signal is generated.

In the present invention, a capacitor discharge ignition circuit or a current interruption type ignition circuit can be used as the ignition circuit. The capacitor discharge type ignition circuit is charged to one polarity by an ignition coil and a voltage obtained by increasing the output voltage of the magnet generator or the output voltage of the magnet generator provided on the primary side of the ignition coil. The circuit includes an ignition energy storage capacitor, and a discharge thyristor provided to discharge a charge of the capacitor through a primary coil of the ignition coil when the capacitor is turned on. In this ignition circuit, when an ignition signal is given to the thyristor, the charge of the ignition energy storage capacitor is discharged to the primary coil of the ignition coil, and this discharge induces a high voltage for ignition in the secondary coil of the ignition coil. I do. Since this high voltage is applied to a spark plug attached to a cylinder of the engine, a spark is generated in the spark plug and the engine is ignited.

The current interruption type ignition circuit has a primary current control switch on the primary side of the ignition coil, and a current is passed through the switch at a position advanced from the ignition position, and an ignition signal is given. At times, the primary current control switch is turned off to induce a high voltage for ignition on the secondary side of the ignition coil.

In any of the ignition circuits, when an ignition signal is applied, the semiconductor switch operates to cause a sudden change in the primary current of the ignition coil, and the change in the primary current causes the secondary current of the ignition coil to change. Induces a high voltage for ignition.

The signal generator generates a reference signal and a fixed ignition position signal once per rotation at a fixed rotation angle position in synchronization with the rotation of the engine. This signal generator is, for example, an induction motor. A slave signal generator can be used. An inductor-type signal generator includes a rotor provided with a reluctor (inductor), and a signal generator that is arranged to face a surface of the rotor where the reluctor is provided. The signal generator includes an iron core having a magnetic pole portion facing the rotor at its tip, a signal coil wound around the iron core, and a permanent magnet magnetically coupled to the iron core. Two pulse-like signals having different polarities are generated in the signal coil due to a change in magnetic flux generated in the iron core when the electron generator starts to oppose the magnetic pole portion of the iron core and when the opposition ends.

When the signal generator as described above is used, of the two signals having different polarities in which signal emission occurs, the signal generated earlier is used as a reference signal, and the signal generated later is used as a fixed ignition position signal. May be used.

The rotation speed detecting means detects the rotation speed of the engine from the generation cycle of the reference signal generated by the signal generator.
Since the generation cycle of the reference signal corresponds to the time of one rotation of the engine, information on the rotation speed of the engine can be obtained from the generation cycle. In order to obtain information on the rotational speed, for example, a counter provided in the microcomputer starts counting clock pulses when each reference signal is generated, and counts the counter value when the next reference signal is generated. And clear the counter,
The time required for one revolution of the engine may be measured. The time data thus obtained may be used as it is as the rotation speed information, or the rotation speed may be calculated from the time data and the calculated value may be used as the rotation speed information. When the time required for one rotation of the engine is used as the rotation speed information, the value of the data of the rotation speed information is inversely proportional to the rotation speed of the engine.

The ignition position calculation means calculates the ignition position in the form of the time required for the engine to rotate from the reference position to the ignition position at the rotation speed detected by the rotation speed detection means. The ignition position calculation means may calculate the ignition position at each rotation speed using a mathematical expression. The ignition position at each rotation speed is calculated by an interpolation method using a map that gives a relationship between the rotation speed and the ignition position. It may be calculated by

When it is determined that the rotation speed of the engine is higher than the set rotation speed, the ignition command signal generating means at the time of steady operation starts measurement of the ignition position calculated at the generation position of the reference signal, and the measurement is performed. Is completed, the ignition command signal is generated. In order to realize the ignition command signal generating means, for example, a counting operation of a counter for counting clock pulses is started when a reference signal is generated, and when the counted value matches a counted value for giving an ignition position. , An ignition command signal may be generated.

When it is determined that the rotation speed is equal to or lower than the set rotation speed (at an extremely low speed of the engine), the extremely low-speed ignition control timer measures from the generation position of the reference signal to the generation position of the fixed ignition position signal. The time required for the engine to rotate is measured, and it is determined from the measured time whether the engine has sufficient momentum for cranking rotation. If the measured time exceeds the permissible upper limit, the generation of the ignition command signal is stopped because the rotation of the crankshaft has no momentum and there is a risk of reverse rotation, and the measured time is less than the permissible upper limit. In such a case, the ignition command signal is generated at the position where the fixed ignition position signal is generated, assuming that the rotation of the crankshaft has sufficient momentum.

When the ignition command signal is generated from the ignition command signal generating means at the time of steady operation or the ignition command signal generating means at the extremely low speed, an ignition signal is given to the ignition circuit through the ignition signal output means to perform the ignition operation.

[0031]

FIG. 1 shows an embodiment of the present invention, in which 1 is a DC converter circuit, 2 is a capacitor discharge ignition circuit, 3 is a microcomputer, and 4 is synchronous with the rotation of an internal combustion engine. The signal coils 5, 5 and 6 in the signal generator for generating the first and second signals Vs1 and Vs2 can recognize the first and second signals Vs1 and Vs2 generated by the signal coil 4 by the microcomputer, respectively. Input signal A1 of the microcomputer 3
A1 and A2 provide interrupt signals INT1 and INT2, and a first and second waveform shaping circuit 7 applies an ignition signal Vi to the ignition circuit 2 when the potential of the output port B of the microcomputer 3 is set to a high level. This is an ignition signal output circuit.

The DC converter circuit 1 has a step-up transformer 1A in which one end of a primary coil is connected to a positive electrode of a battery 8 whose negative electrode is grounded and a primary current is supplied from the battery.
A switching circuit 1B connected in series to a primary coil of the step-up transformer 1A to turn on and off a primary current of the step-up transformer, an oscillation circuit 1C for supplying a rectangular wave drive signal to the switch circuit 1B, A diode D1 for half-wave rectifying the output of the secondary coil. In the illustrated example, the source is grounded, and the drain is connected to the other end of the primary coil of the step-up transformer 1A.
A switch circuit 1B is constituted by the OSFET F1,
A drive signal is given to the gate of the MOSFET from the oscillation circuit 1C. One end of the secondary coil of the step-up transformer 1A is grounded, and the other end of the secondary coil is connected to the anode of a diode D1.

In the DC converter circuit 1 described above,
The MOSFE is driven by a drive signal given from the oscillation circuit 1C.
TF1 is turned on and off. As a result, the primary current of the step-up transformer 1A is interrupted, so that a boosted voltage is induced in the secondary coil of the step-up transformer 1A. In the positive half cycle of the induced voltage, the voltage is applied to the ignition circuit 2 through the diode D1. Is supplied.

The capacitor discharge type ignition circuit 2 includes an ignition coil IG, a diode D2, an ignition energy storage capacitor C1, a discharge thyristor Th1, and a resistor Ro connected between the gate and cathode of the thyristor Th1. The output voltage of the ignition coil IG is applied to a spark plug P attached to a cylinder of an engine (not shown). In this ignition circuit, a capacitor charging circuit is constituted by the circuit of the DC converter circuit 1 → the capacitor C1 → the diode D2 and the primary coil of the ignition coil IG → the DC converter circuit 1. The output voltage of the DC converter circuit 1 makes the capacitor C1 available. It is charged to the polarity shown.

When the ignition signal Vi is applied to the gate of the thyristor Th1 at the ignition position of the internal combustion engine, the thyristor conducts, and the electric charge of the capacitor C1 is discharged through the thyristor Th1 and the primary coil W1 of the ignition coil. As a result, a high voltage is induced in the secondary coil W2 of the ignition coil. This high voltage causes a spark in the spark plug P to ignite the engine.

The signal coil 4 is provided in a signal generator provided to rotate synchronously with the internal combustion engine.
As shown in (A), a reference position set at a position where the phase is advanced from the top dead center TDC of the internal combustion engine (the maximum advance position of the ignition position or a position where the phase is slightly advanced from the maximum advance position). ) The first signal Vs1 is generated at θs1, and the fixed ignition position (5% higher than the top dead center than the top dead center) suitable as the ignition position during idling is performed.
A second signal Vs2 is generated at θs2 (a position advanced by 13 ° to 13 °). In this example, the first signal Vs1 and the second signal Vs1
s2 is composed of a negative pulse signal and a positive pulse signal, respectively, and the first signal Vs1 and the second signal Vs2
Are input to the first waveform shaping circuit 5 and the second waveform shaping circuit 6, respectively.

Here, the signal generation position means a position where the signal reaches a predetermined threshold level.

The waveform shaping circuit 5 has an emitter grounded,
An NPN transistor TR1 having a collector connected to a positive output terminal of a DC power supply (not shown) through a resistor R1,
A resistor R2 connected between the base and emitter of the transistor TR1, a diode D3 connected in parallel across the resistor R2 with the anode facing the ground, a positive output of a DC power supply (not shown) and the base of the transistor TR1. A resistor R3 connected between the terminal and a transistor TR1
And a parallel circuit of a resistor R5 and a capacitor C2, one end of which is connected to the cathode of the diode D4. The other end of the parallel circuit of the resistor R5 and the capacitor C2 is connected to the signal coil 4. Connected to non-ground terminal.

The waveform shaping circuit 6 includes an NPN transistor TR whose emitter is grounded and whose collector is connected to a positive output terminal of a DC power supply (not shown) through a resistor R1 '.
1 ', a resistor R2' connected between the base and emitter of the transistor TR1 ', a diode D4' having a cathode connected to the base of the transistor TR1, a resistor R5 'having one end connected to the anode of the diode D4', and The other end of the parallel circuit of the resistor R5 'and the capacitor C2' is connected to the non-ground terminal of the signal coil 4.

When a first signal Vs1 of negative polarity is induced in the signal coil 4 and the signal Vs1 exceeds a threshold level substantially determined by the residual voltage at both ends of the capacitor C2 at the reference position θs1, the signal coil 4 D3 and D4
A current flows through the parallel circuit of the resistor R5 and the capacitor C2, and a voltage drop occurs across the diode D3.
Since the base and the emitter of the transistor TR1 are reverse-biased only while the signal Vs1 exceeds the threshold level and a voltage drop occurs across the diode D3, the transistor TR1 which has been conducting until then is short-lived. It is shut off for a while. When the transistor TR1 is turned off, the potential of the collector of the transistor TR1 changes from a low level (substantially the ground level) to a high level, so that a pulse waveform signal is obtained at the collector of the transistor TR1. This signal is the external interrupt signal INT1
To the input port A1 of the microcomputer 3.

A second signal V having a positive polarity is applied to the signal coil 4.
s2 is induced, and when the signal Vs2 exceeds a threshold level substantially determined by the residual voltage across the capacitor C2 'at the fixed ignition position .theta.s2 set at a position suitable for the ignition position at idling, the signal coil 4 Resistance R5 '
A current flows between the parallel circuit of the capacitor C2 ', the diode D4' and the base-emitter of the transistor TR1 ', and while the signal Vs2 exceeds the threshold level, the transistor TR1' which has been cut off until then.
Becomes conductive. As a result, the transistor TR1 '
A signal having a pulse waveform falling from a high level to a low level is obtained at the collector of the external interrupt signal IN.
The input port A2 of the microcomputer 3 is defined as T2.
Given to.

The microcomputer 3 includes a CPU 3a,
Interrupt control circuit 3b, random access memory (RA
M) 3c, a read-only memory (ROM) 3d, a counter 3e, a comparator 3f, a register 3g, a latch circuit 3h, an edge detection circuit 3i, and a flip-flop circuit 3j, and input ports A1 and External interrupt signal IN given through A2
T1 and INT2 are input to the interrupt control circuit 3b. .

The ignition signal output circuit 7 comprises an NPN transistor TR2 whose emitter is grounded,
2 whose collector is connected to the base through a resistor R6
And an NP transistor TR3. The base of the transistor TR2 is connected to the output port B of the microcomputer through a resistor R7, and a resistor R8 is connected between the base of the transistor TR2 and the ground. The emitter of the transistor TR3 is connected to the positive output terminal of a DC power supply circuit (not shown), and the base of the transistor TR3 is connected to the positive terminal of the DC power supply through a resistor R9. The anode of a diode D5 is connected to the collector of the transistor TR3 through a resistor R10, and the cathode of the diode D5 is connected to the gate of the thyristor Th1 of the ignition circuit 2.

In the ignition device shown in FIG. 1, when an external interrupt signal INT1 is given to the interrupt control circuit 3b,
The flip-flop circuit 3j is reset, and the output of its positive logic output terminal Q becomes "0". At this time, if the output of the flip-flop circuit 3j is permitted, the output of the output port B of the microcomputer becomes "0". Further, when the external interrupt signal INT1 is generated, the edge detection circuit 3i detects the rising edge and the latch circuit 3h
To work. The latch circuit 3h outputs the interrupt signal INT1
Latches the count value of the counter 3e (count value of the clock pulse) at the time when the error occurs. The interrupt control circuit 3b latches the count value of the counter 3e by the latch circuit 3h and clears the counter 3e. Since the counter is cleared immediately after latching the count value of the counter 3e, the latched count value corresponds to the time required for one revolution of the engine. In this embodiment, the count value itself is used as speed data Ne indicating the rotation speed of the engine.
Therefore, the speed data Ne indicates a larger value as the rotation speed is lower.

A predetermined program and a map used for calculating the ignition position are stored in the ROM 3d of the microcomputer, and the main routine shown in FIG. 2 and the interrupt routine shown in FIGS. Be executed.

In the main routine shown in FIG. 2, when the power supply is established, each section is first initialized (initialized), and thereafter, the ignition position θig at each rotation speed is calculated, and the calculated ignition position θig is stored in the RAM. Repeat the process. The calculation of the ignition position is performed by an interpolation method using a map stored in the ROM 3d. By the process of calculating the ignition position, an ignition position calculation means is realized. The ignition position θig is calculated in the form of the time (count value of clock pulse) required for the engine to rotate from the reference position to the ignition position at each rotation speed.

When the external interrupt signal INT1 is given to the interrupt control circuit 3b at the reference position θs1, the interrupt processing shown in FIG. 3 is performed. In this interrupt processing, first, the flag 1 is set to "0", and then the count value of the counter (the number of clock pulses counted by the counter during one rotation of the engine) latched by the latch circuit 3h is used as the rotation speed of the engine. The speed data Ne is stored in the RAM 3c. By this process, a rotation speed detecting means is realized. Next, it is determined whether or not the speed data Ne is equal to or greater than the set value N1.
Here, the set value N1 gives an upper limit (for example, 2000 rpm) of an extremely low speed region (idling region) of the engine. As a result of comparing the speed data Ne with the set value N1, Ne
If .gtoreq.N1 (when the rotation speed is equal to or lower than the set rotation speed), the output of the flip-flop circuit 3j is inhibited from being output from the output port B, and then the flag 2 is set to "1".
To return to the main routine. As a result of comparing the speed data Ne with the set value N1, when Ne <N1 (when the rotation speed exceeds the set rotation speed), the output of the flip-flop circuit 3j is not output from the output port B. After the permission, the flag 2 is set to "0", the calculated ignition position θig is transferred to the register 3g, and then the process returns to the main routine.

When the signal coil 4 generates the second signal Vs2 and generates the interrupt signal INT2, the interrupt routine shown in FIG. 4 is executed. In this interrupt routine, first, it is determined whether or not the flag 2 is "1". As a result, if the flag 2 is not "1" (if the engine speed exceeds the set speed), the main routine is executed. Return to routine. When the flag 2 is “1” (when the rotation speed is equal to or lower than the set rotation speed), the count value T of the counter 3e at that time is set.
n (the time required for the crankshaft to rotate from the reference position θs1 to the fixed ignition position θs2) is fetched, and it is determined whether the fetched count value Tn is larger or smaller than the allowable upper limit value Tns. The permissible upper limit Tns of the counted value gives the permissible lower limit of the rotation speed during the rotation of the engine from the reference position θs1 to the fixed ignition position θs2 at an extremely low speed. Count value T
When the count value Tn is larger than the allowable upper limit value Tns as a result of comparing the n with the allowable upper limit value Tns (the rotation speed during the rotation of the crankshaft from the reference position to the fixed ignition position is lower than the allowable lower limit value, and If there is a possibility that the engine will reverse if ignition is performed at the ignition position θs2), the process returns to the main routine without doing anything.

As a result of judging whether the count value Tn of the counter 3e is larger or smaller than a reference value Tns giving a set time,
If the count value Tn is equal to or less than the allowable upper limit value Tns (the rotational speed during the rotation of the crankshaft from the reference position to the fixed ignition position is equal to or greater than the allowable lower limit value, and the engine may reverse even if ignited at the fixed ignition position θs2) ), The output of the port B of the microcomputer is set to "1", and a value obtained by adding a constant value α to the current count value of the counter 3e is stored in the register 3g.
Transfer to Here, α corresponds to the signal width of the ignition signal. After transferring the value obtained by adding the fixed value α to the count value of the counter 3e to the register 3g, the flag 1 is set to “1” and the process returns to the main routine.

When the output of the port B is set to "1" in the interrupt routine of FIG. 4, a base current flows through the transistor TR2 of the ignition signal output circuit 7, and the transistor TR2
Since transistor 2 is turned on, transistor TR3 is turned on, and an ignition signal is supplied from a DC power supply circuit (not shown) to thyristor Th1 through transistor TR3, resistor R10 and diode D5. After the counter 3e counts the count value corresponding to the above α after the ignition signal is given to the thyristor Th1, the count value of the counter is stored in the register 3g.
, The comparator 3f supplies a set signal to the flip-flop circuit 3j to set the output Q of the flip-flop circuit to 1 and the interrupt control circuit 3j.
b to the interrupt signal INT3. When Ne ≧ N1 (when the rotation speed is equal to or lower than the set rotation speed), the output of the flip-flop circuit is prohibited. Does not affect

The interrupt control circuit 3b outputs the interrupt signal INT
When 3 occurs, the interrupt routine shown in FIG. 5 is executed. When Ne.gtoreq.N1 (at an extremely low speed of the engine), when the count value of the counter 3e becomes equal to the count value set in the register 3g in the interrupt routine of FIG. 4 (the second signal Vs2 is generated). (When a time corresponding to the signal width α has elapsed), an interrupt signal INT3 is generated, and the interrupt routine of FIG. 5 is executed. In the interrupt routine of FIG. 5, it is first determined whether the flag 1 is "0". When Ne ≧ N1, the flag 1 is set to “1” in the interrupt routine of FIG.
Is set to "0" to turn off the transistors TR2 and TR3 (after the ignition signal is extinguished), and the process returns to the main routine.

When the rotational speed of the engine exceeds the set value, an interrupt signal INT3 is generated when the count value of the counter 3e matches the count value of the ignition position θig set in the register 3g in the interrupt routine of FIG. Fig. 5
Is executed. At this time, since the flag 1 is "0" (the flag 1 is not set to "1" in the interrupt routine of FIG. 4 because Ne <N1), the current count value of the counter is α (signal width). Is transferred to the register 3g, the flag 1 is set to "1", and the process returns to the main routine. Thereafter, when a count value corresponding to the signal width α of the ignition signal is counted and the interrupt signal INT3 is generated, the interrupt routine of FIG. 5 is executed again. At this time, since the flag 1 is "1", the output of the port B of the microcomputer is forcibly set to "0" and the process returns to the main routine.

As described above, in the present invention, when the rotation speed of the engine is equal to or lower than the set rotation speed (at an extremely low speed).
By determining whether or not the time required for the crankshaft to rotate from the reference position to the fixed ignition position is equal to or less than the allowable upper limit, the engine speed near the fixed ignition position is equal to or greater than the allowable lower limit. It is determined whether or not there is, and the ignition operation is performed at the fixed ignition position θs2 only when the rotation speed of the engine near the fixed ignition position is equal to or higher than the allowable lower limit. That is,
As shown in the left end of FIG. 7, when the engine is started, the rotation speed near the fixed ignition position θs2 is lower than the allowable lower limit, and the time Tn required for the engine to rotate from the reference position θs1 to the fixed ignition position θs2. However, if it exceeds the allowable upper limit value Tns, the ignition operation is not performed at the fixed ignition position θs2, and the engine is misfired. As shown in the center and the right end of FIG. 7, the time Tn required for the engine to rotate from the reference position θs1 to the fixed ignition position θs2 when the rotation speed near the fixed ignition position is equal to or higher than the allowable lower limit when the engine is started. Is smaller than the allowable upper limit value Tns, the ignition operation is performed at the fixed ignition position θs2, and the engine starts.

With this configuration, when the engine is running at an extremely low speed, there is sufficient momentum for the rotation of the engine near the fixed ignition position near the top dead center. The engine is ignited only when there is no danger of reversing, and there is no momentum in rotation near the fixed ignition position, and if ignition is performed at the fixed ignition position, the engine will misfire if there is a danger that the engine will be reversed. In addition, the reversal of the engine can be reliably prevented.

In this embodiment, in the interrupt routine shown in FIG. 3, a process of latching the count value of the counter and taking in the latched count value realizes a rotational speed detecting means, and calculates the ignition position θig of the main routine. The process implements ignition position calculation means.

In the interrupt routine of FIG. 3, it is determined whether or not the rotation speed detected by the rotation speed detecting means is equal to or lower than the set rotation speed by the process of determining the magnitude relationship between the speed data Ne and the set value N1. Is realized.

Further, in the interrupt routine shown in FIG. 3, the output of the flip-flop circuit is permitted and θig is transferred to the register, and the interrupt routine shown in FIG. A steady operation time ignition command signal generation means for generating an ignition position signal at the ignition position calculated by the ignition position calculation means when it is determined that the ignition command signal has exceeded the threshold value is realized.

In the interrupt routine of FIG. 4, prior to performing the process of comparing the count value Tn of the counter with its allowable upper limit value Tns, a process of taking in the count value Tn (not shown in FIG. 4). ), When the rotation speed determination means determines that the rotation speed is equal to or lower than the set rotation speed, an extremely low speed that measures the time required for the engine to rotate from the reference signal generation position to the fixed ignition position signal generation position. Time ignition control timing means is realized.

Further, the process of comparing the count value Tn with the allowable upper limit value Tns in the interrupt routine of FIG.
Is set to “1”, the value obtained by adding α to the count value of the counter is transferred to the register, and the flag 1 is set to “1”.
5 and the interrupt routine of FIG. 5, when it is determined that the rotation speed is equal to or lower than the set rotation speed and the time Tn measured by the timer is equal to or less than the allowable upper limit value Tns. An ignition command signal is generated at the position where the fixed ignition position signal is generated, and the ignition is performed when it is determined that the rotation speed is equal to or less than the set rotation speed and the time measured by the timer is longer than the allowable upper limit. An extremely low-speed ignition command signal generating means for stopping generation of the command signal is realized.

In the above example, the ignition circuit 2 is configured to operate using the DC converter circuit 1 as a power supply. However, the ignition circuit 2 uses the exciter coil provided in the magnet generator attached to the internal combustion engine as a power supply. It is needless to say that the present invention can also be applied to the case where.

[0061]

As described above, according to the present invention, the ignition signal is generated at the fixed ignition position set before the top dead center of the engine when the engine is at extremely low speed. The engine can be stably operated at a fixed position before the top dead center.

According to the present invention, when the rotation speed of the engine is equal to or lower than the set rotation speed, the time required from when the signal generator generates the reference signal to when the fixed ignition position signal is generated is measured. , because the time has to generate an ignition signal at the occurrence position of the fixed ignition position signal only when: the allowable upper limit value, there is no momentum to the rotation of the crankshaft at startup, when the directly perform the ignition operation organizations There is an advantage that the engine can be misfired when there is a possibility of reverse rotation, and the engine can be reliably prevented from reverse rotation at startup.

[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 a main routine of a program executed by a microcomputer in the embodiment of the present invention.

FIG. 3 is a flowchart showing an interrupt routine of a program executed by the microcomputer when the signal generator generates a reference signal in the embodiment of the present invention.

FIG. 4 is a flowchart showing an interrupt routine of a program executed by the microcomputer when the signal generator generates a fixed ignition position signal in the embodiment of the present invention.

FIG. 5 is a flowchart showing an interrupt routine of a program executed by the microcomputer when the count value of the counter matches the contents of a register in the embodiment of the present invention.

FIG. 6 is a waveform diagram showing a waveform of a signal generated by a signal generator and a waveform of an output signal of a waveform shaping circuit in the embodiment of FIG.

FIG. 7 is a waveform diagram for explaining ignition control at an extremely low speed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 DC converter circuit 2 Ignition circuit 3 Microcomputer 4 Signal coil 5 Waveform shaping circuit 6 Waveform shaping circuit 7 Ignition signal output circuit

Claims (1)

(57) [Claims] 1. An ignition circuit for controlling a primary current of an ignition coil to generate a high voltage for ignition when an ignition signal is applied, and an ignition circuit set at a position advanced in phase from a top dead center of the internal combustion engine. A signal generator that generates a reference signal and a fixed ignition position signal at a fixed ignition position set at a reference position and a fixed ignition position set at a position delayed in phase from the reference position and advanced in phase from the top dead center, respectively, the reference signal Rotation speed detection means for detecting the rotation speed of the internal combustion engine from the occurrence cycle of the internal combustion engine; ignition position calculation means for calculating the ignition position of the internal combustion engine with respect to the rotation speed detected by the rotation speed detection means; A rotation speed determining unit that determines whether the rotation speed detected by the unit is equal to or less than a set rotation speed; and the rotation speed determination unit determines that the rotation speed exceeds the set rotation speed. When a steady operation time ignition command signal generating means for generating an ignition command signal at the ignition position calculated by the ignition position calculating means, and when the rotation speed determination means determines that the rotation speed is equal to or less than a set rotation speed. An extremely low-speed ignition control timing means for measuring a time required for the engine to rotate from the reference signal generation position to the fixed ignition position signal generation position, and it is determined that the rotation speed is equal to or lower than a set rotation speed. When it is determined that the time measured by the timing means is equal to or less than the allowable upper limit value, an ignition command signal is generated at the position where the fixed ignition position signal is generated, and the rotational speed is equal to or less than a set rotational speed. When it is determined that the time measured by the timing means exceeds the allowable upper limit value, the generation of the ignition command signal is stopped, and the generation of the ignition command signal is stopped at an extremely low speed. An ignition device for an internal combustion engine, comprising: a generation unit; and an ignition signal output circuit that supplies an ignition signal to the ignition circuit when the ignition command signal is generated.