JP2003176751A - Internal combustion engine igniter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine igniter which detects a detonation without using a high-cost circuit such as a bandpass filter, and controls ignition time for suppressing the detonation. <P>SOLUTION: In this igniter, outputs of combustion pressure sensors 8A, 8B are inputted to A/D conversion input ports of an MPU 3 through peak hold circuits 10A, 10B to obtain digital values corresponding to peak values of the outputs of the sensors 8A, 8B. By comparing the digital values with a decision value, the detonation is detected. When it is detected that the detonation occurs in a prescribed frequency, an ignition time angle is delayed. When it is detected that the detonation is eliminated, or when the generation frequency is reduced, the ignition time angle is advanced. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine ignition device having a function of suppressing the generation of detonation.

[0002]

2. Description of the Related Art In an internal combustion engine, after the air-fuel mixture in a cylinder is ignited by a spark plug, burned gas compresses surrounding unburned gas in the process of propagating the flame and the pressure of the unburned gas is increased. If the temperature is raised excessively, the temperature of the unburned gas rises due to the rise in pressure and radiant heat from the flame,
It is known that the unburned gas self-ignites, causing explosive abnormal combustion in the cylinder. This phenomenon is called detonation and causes damage to the engine. This phenomenon occurs when the advance amount of ignition timing is large, or when the air-fuel ratio of the air-fuel mixture is shifted to the lean side and the cooling effect of the piston by the latent heat of vaporization of fuel is weak, so retard the ignition timing. Alternatively, it can be suppressed by controlling the air-fuel ratio to the rich side, but generally, the ignition timing is set to the retard side in consideration of the variation in the air-fuel ratio.

However, in an internal combustion engine, the maximum output is obtained immediately before detonation occurs or when detonation is slightly generated. Therefore, if the ignition timing is set to the retard side, Can not derive high performance from.

Therefore, in a high-performance engine used for a two-wheeled vehicle, a snowmobile, etc., the ignition timing is set so that the engine is operated immediately before detonation occurs or in a state where detonation occurs to some extent, and detonation is detected. The ignition timing is retarded when it is turned on, and is advanced when the detonation is stopped. By performing such control, it is possible to suppress the generation of detonation and bring out high performance from the engine without sacrificing the output of the engine.

In order to perform such control, it is necessary to detect detonation. Usually, detonation is detected by a seat type combustion pressure sensor (GPS) which is fastened together with an ignition plug and attached to a cylinder of an engine. This combustion pressure sensor uses a piezoelectric element as a transducer that converts pressure into voltage, and has a frequency of 10 [kHz] to 20 [kHz when detonation occurs.
z], an oscillating voltage having a peak value of 20 [V] or more is output as a combustion pressure detection signal.

In the conventional ignition device having the function of suppressing the detonation, when the detonation occurs, 20
After converting the output signal voltage of the combustion pressure sensor exceeding [V] into a low voltage signal by the voltage conversion circuit, this signal is set to 1
Input to a band pass filter that passes only the signal of the frequency of 0 [kHz] to 20 [kHz], and input the level of the signal of 10 [kHz] to 20 [kHz] output from the filter to the comparator. The detonation detection signal was obtained by comparing with the threshold value. And
By inputting this detection signal to the external interrupt input terminal of the MPU for ignition timing control, the MPU interrupts the program being executed, and the interrupt causes the process of counting the number of times detonation occurs. Thus, the ignition timing is retarded when it is detected that detonation has occurred a predetermined number of times.

[0007]

As described above, in the conventional ignition device having the detonation suppressing function, the output of the combustion pressure sensor is passed through the bandpass filter to obtain only the signal in the frequency band used for detecting the detonation. After getting
Since the detonation detection signal is obtained by comparing the signal with a threshold value by a comparator, an expensive bandpass filter is required and a troublesome adjustment work for adjusting the comparison level of the comparator is required. It was necessary and unavoidable to be costly.

An object of the present invention is to suppress detonation by detecting detonation on the software of the MPU and controlling the ignition timing retardation without using a bandpass filter or a comparator. Another object of the present invention is to provide an ignition device for an internal combustion engine.

[0009]

SUMMARY OF THE INVENTION The present invention is an ignition circuit for generating a high voltage for ignition when an ignition signal is applied,
The ignition angle is set as an ignition process section for performing a process for generating an ignition signal in a crank angle range between a reference position set at a position advanced from the top dead center position of the internal combustion engine and the top dead center position. The present invention is applied to an ignition device for an internal combustion engine provided with an MPU which constitutes an ignition control means for performing processing including calculation of ignition timing in the processing section, measurement of the calculated ignition timing, and generation of an ignition signal.

In the present invention, the combustion pressure sensor that detects the combustion pressure in the cylinder of the internal combustion engine and outputs a detection signal that exceeds a predetermined level when detonation occurs, and the peak value of the detection signal that the combustion pressure sensor outputs. A peak value detection circuit for detecting and outputting a voltage signal corresponding to the peak value;
A / D conversion means for converting the voltage signal output from this peak value detection circuit into a digital value, and combustion pressure digital value reading for repeatedly reading the digital value in a section of a constant crank angle range delayed from the top dead center position. And a detonation detection unit that compares the digital value with a determination value for determining whether or not detonation has occurred, and detects that detonation has occurred when the digital value exceeds the determination value. When the number of times the detonation detection means detects the occurrence of detonation within the retard angle determination time is equal to or greater than the set retard angle determination number, the ignition timing calculated by the ignition control means is set by the set retard angle amount. The number of times the detonation detecting means detects the detonation within the set advance condition determination time When the number of less or zero, provided a detonation inhibition ignition timing control means for controlling the ignition timing so as to only advance advance amount, which is set the ignition timing.

As described above, in the conventional ignition device having the detonation suppressing function, the bandpass filter for extracting the signal in the frequency band effective for detecting the detonation from the output of the combustion pressure sensor and the output of the filter are used. A comparator that detects the occurrence of detonation by comparing with a threshold value is provided outside the MPU, and when the comparator detects the occurrence of detonation, interrupts the MPU to count the number of times detonation occurs. Therefore, a bandpass filter and a comparator are required. On the other hand, in the present invention, the peak value of the output voltage of the voltage conversion circuit having a magnitude corresponding to the output signal of the combustion pressure sensor is converted into a digital value, and this digital value is a judgment value prepared in advance on software. To detect detonation by comparing with
The cost can be reduced by omitting the bandpass filter and the comparator.

Since the MPU is originally provided for controlling the ignition timing, when the detonation is detected by performing the A / D conversion process and the determination process on the software as described above, It is necessary to devise to perform the detonation detection processing without interfering with the processing necessary for controlling the ignition timing, such as calculating the ignition timing, measuring the calculated ignition timing, and generating the ignition signal. .

In the present invention, generally, the ignition processing section in which the MPU performs processing for controlling the ignition timing is a reference position and a top dead center position set at a position advanced from the top dead center position of the internal combustion engine. In the ignition process, the detonation of the internal combustion engine occurs in a region outside the ignition process region (a region with a certain angular range after top dead center). The combustion pressure sensor is read in the section deviating from the section and A /
The D conversion process and the determination process are performed. Therefore, according to the present invention, the occurrence of detonation can be detected by software without affecting the control of the ignition timing, and the ignition device can have the detonation suppressing function without increasing the cost. .

The peak value detection circuit detects the peak value of the detection signal voltage output by the combustion pressure sensor as a voltage signal of a level that can be input to the MPU, and outputs the voltage signal (the detection signal output of the combustion pressure sensor). The voltage signal having a voltage value corresponding to the peak value is at least A
The one configured to hold for the time required for the / D conversion is used.

Such a peak value detection circuit is, for example, a voltage conversion circuit that lowers the voltage level of the detection signal output from the combustion pressure sensor to a level close to the level that can be input to the MPU,
A peak hold circuit including a hold capacitor and a circuit that charges the hold capacitor to the peak value of the output voltage of the voltage conversion circuit, and a discharge circuit that discharges the hold capacitor with a constant time constant are provided. It is possible to use a device configured to generate a voltage signal corresponding to the peak value of the output voltage of the voltage conversion circuit.

In this case, a discharge circuit for discharging the hold capacitor with a constant time constant is provided. The discharge time constant of this discharge circuit is set so that the voltage across the hold capacitor can be held at the peak value during the time required for the A / D conversion means to complete the A / D conversion process. .

As described above, the voltage corresponding to the output voltage of the combustion pressure sensor is held by the peak hold circuit and A / D
If the conversion means is provided, the A / D conversion processing can be surely performed even when the conversion speed of the A / D conversion is slow, and the detonation can be surely detected.

Further, when the peak hold circuit as described above is used, a reset circuit configured to discharge the charge of the hold capacitor through a reset switch capable of on / off control, and a voltage signal by the A / D conversion means. Reset switch control means for controlling the reset switch so that the reset switch is kept in the OFF state until the A / D conversion is completed and the reset switch is turned on after the A / D conversion is completed. And are preferably provided.

With this configuration, the terminal voltage of the hold capacitor can be reliably held until the A / D conversion is completed, so that the conversion speed of the A / D conversion means is slow. The detonation can be detected reliably.

Further, the peak value detection circuit is provided with a voltage conversion circuit for lowering the voltage level of the detection signal output from the combustion pressure sensor to a level close to the level at which it can be input to the MPU, and a hold capacitor and a sample signal supplied from the MPU. The sample-hold circuit having a circuit for charging the hold capacitor up to the peak value of the output voltage of the voltage conversion circuit. In this case, the combustion pressure digital value reading means is configured to repeatedly apply the sample signal to the sample hold circuit when the crank angle of the internal combustion engine is out of the ignition processing section.

Further, in the present invention, the ignition timing calculated by the ignition control means is set when the digital value obtained from the A / D conversion means continues for the set determination time in which the state is less than the threshold value. Further, it is preferable to further provide a combustion pressure sensor abnormal point ignition timing control means for retarding the ignition timing by the retard amount.

In this way, if the combustion timing sensor abnormal timing ignition timing control means is provided, the output line of the combustion pressure sensor is broken or the output of the combustion pressure sensor is broken. When the detonation cannot be detected because it cannot be taken in, it is possible to prevent the engine from being damaged by the occurrence of the detonation.

To simplify the configuration, the MPU is A
It is preferable to use one having a built-in / D converter. MP
When the A / D converter is built in U, the voltage signal output from the peak value detection circuit is input to the A / D conversion input port of the MPU, and the voltage is output by the A / D converter built in the MPU. The A / D conversion means is configured to perform A / D conversion of the signal.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a hardware configuration of an ignition device for a two-cylinder two-cycle internal combustion engine to which the present invention is applied. In FIG. 1, reference numeral 1 denotes an AC voltage induced in synchronization with the rotation of the internal combustion engine. An exciter coil, 2 is an ignition circuit that uses the exciter coil 1 as a power source to generate a high voltage for ignition when an ignition signal is applied, 3 is an MPU (microprocessor) that constitutes ignition control means, and 4 is an exciter coil 3 is a power supply circuit for converting the output voltage of No. 3 into a constant DC voltage.

Further, 5 is a pulser coil for generating the first pulse signal Vs1 and the second pulse signal Vs2 at a specific rotational angle position of the internal combustion engine, and 6 and 7 are pulser coils 5 respectively.
Are generated by the first and second waveform shaping circuits for converting the first pulse signal Vs1 and the second pulse signal Vs2 generated by the MPU into signals that can be recognized by the MPU and inputting them as interrupt signals to the interrupt terminals INT1 and INT2 of the MPU. is there.

Further, 8A and 8B are respectively the first of the engine.
The first and second combustion pressure sensors (GPS) for detecting the combustion pressures of the cylinder and the second cylinder, the first and second combustion pressure sensors (GPS) 9A and 9B, respectively.
And the first and second voltage conversion circuits 10A and 1 that lower the voltage level of the detection signal output by the second combustion pressure sensors 8A and 8B to a level near the level that can be input to the MPU 3.
0B is a first and second peak hold circuit that detects and holds a voltage signal corresponding to the peak value of the voltage obtained from the first and second voltage conversion circuits, 11A and 11B, respectively.
Reference characters B are first and second discharge circuits for discharging the hold capacitors of the first and second peak hold circuits, respectively.
The voltage signals output by 0B are input to the A / D conversion input ports A1 and A2 of the MPU, respectively.

Explaining each part in detail, the exciter coil 1 is provided in a magnet generator attached to an internal combustion engine, and the positive half-wave output voltage Ve1 and the negative half-wave are synchronized with the rotation of the engine. Of the output voltage Ve2 is induced. The current feedback diodes D1 and D2 whose anodes are grounded are connected between one end of the exciter coil 1 and the ground and between the other end and the ground, respectively.

The illustrated ignition circuit 2 is a well-known capacitor discharge type circuit, and is provided with an ignition coil IG and an output voltage V of the positive half-wave of the exciter coil 1 provided on the primary side of the ignition coil.
An ignition capacitor Ci charged to the polarity shown by e1
When the ignition signal is given, it conducts and the capacitor Ci
The thyristor Thi as a discharge switch provided so as to discharge the electric charge of 1 through the primary coil of the ignition coil IG constitutes a main part.

In the illustrated example, one end of the primary coil of the ignition coil is grounded, one end of the ignition capacitor Ci is connected to the other end of the primary coil of the ignition coil, and the thyristor is connected between the other end of the capacitor Ci and the ground. Thi is connected with its cathode facing the ground side. The cathode of a diode D3 whose anode is connected to one end of the exciter coil 1 is connected to the other end of the capacitor Ci, and a diode D4 whose cathode is grounded is connected to both ends of the primary coil of the ignition coil IG. .

A diode D is provided at the gate of the thyristor Thi.
The cathode of diode 5 is connected, and the anode of diode D5 is connected to the collector of PNP transistor TR1 through resistor R1. The emitter of the transistor TR1 is connected to the output terminal of the power supply circuit 4, and the base is connected to the port P1 of the MPU 3 through the resistor R2. In this example, the transistor TR1, the diode D5, and the resistors R1 and R2 give a trigger signal to the gate of the thyristor Thi when the MPU3 generates an ignition signal from the port P1 (when the potential of the port P1 is set to the L level). A thyristor trigger circuit is configured.

The operation of the illustrated ignition circuit 2 is as follows. When the exciter coil 1 induces a positive half-wave output voltage Ve1, the exciter coil 1-diode D3-ignition capacitor Ci-diode D4 and ignition coil IG.
A current flows in the path of the primary coil-diode D2-exciter coil 1 to charge the ignition capacitor Ci to the polarity shown in the figure. MPU3 is port P1 at engine ignition timing
The potential of is changed from H level (high level) to L level (low level) and an ignition signal is generated (the potential of the port P1 is lowered to the ground potential). When the MPU generates an ignition signal, the transistor TR1 becomes conductive, so the power supply circuit 4
Applies a trigger signal to the thyristor Thi from the transistor TR1, the resistor R1 and the diode D5. At this time, if the ignition capacitor Ci is charged to the polarity shown in the figure, a forward voltage is applied between the anode and cathode of the thyristor Thi, so that the thyristor Thi becomes conductive and is accumulated in the ignition capacitor Ci. Charge is discharged through the thyristor Thi and the primary coil of the ignition coil IG. This discharge induces a high voltage for ignition in the secondary coil of the ignition coil IG. In this example, the ignition coil IG is used as a simultaneous ignition coil, and the ignition plug PL1 and the first plug attached to the first cylinder of the engine are connected between one end and the ground and between the other end and the ground of the secondary coil of the ignition coil IG, respectively. A spark plug PL2 attached to the two cylinders is connected. Therefore, when a high voltage for ignition is induced in the secondary coil of the ignition coil, a spark is simultaneously generated in the spark plugs PL1 and PL2, and the mixture of the first cylinder and the second cylinder of the engine, which is the cylinder at the ignition timing, is mixed. I am ignited.

The power supply circuit 4 is connected between the other end of the exciter coil 1 and the ground through a diode D6, and the power supply capacitor C1 between the other end of the exciter coil and the ground with its cathode facing the ground side. A voltage adjusting thyristor Th1 and a resistor R connected in parallel at both ends of a capacitor C1.
A voltage detection circuit consisting of a series circuit of 3 and R4, and a resistor R
Zener diode ZD1 connected between the connection point of 3 and R4 and the gate of thyristor Th1, and thyristor T
It consists of a resistor R5 connected between the gate and cathode of h1. In this power circuit, the exciter coil 1
The negative half-wave output voltage Ve2 of diodes D6 and D6
The capacitor C1 is charged to the polarity shown in FIG. 1 through 1, and a DC output voltage Vb is generated across the capacitor C1.
When the output voltage Vb reaches the set value, the Zener diode ZD1 becomes conductive and the thyristor Th1 becomes conductive, so that the charging of the capacitor C1 is stopped. When the output voltage Vb becomes less than the set value, the Zener diode ZD1 becomes non-conductive, so that the instantaneous value of the negative half-wave output voltage of the exciter coil drops and the anode current of the thyristor Th1 becomes less than the holding current. Then, the thyristor Th1 is turned off. When the exciter coil generates a negative half-wave output voltage, the capacitor C1 is charged again and the output voltage Vb rises. By these operations, the DC output voltage Vb is maintained at the set value.

The output voltage of the power supply circuit 4 is applied as a power supply voltage to the power supply terminals of the respective parts including the power supply terminal of the MPU 3.

The pulsar coil 5 is provided in a well-known pulsar (signal generator) that detects a reluctor provided in a rotor attached to a crankshaft of an internal combustion engine and generates a pulse signal, and the pulsar rotates the reluctor. When the front edge and the rear edge in the direction are detected, pulse signals having different polarities are output.

In this example, the rotor of the signal generator has two reluctors corresponding to the two cylinders of the engine, respectively.
It is provided at intervals of 0 degree. Therefore, pulsar coil 5
As shown in FIG. 3, while the crankshaft makes one revolution,
The first and second pulse signals Vs1 and Vs2 are generated twice at 180 ° intervals. In FIG. 3, pulse signals Vs1 and Vs2 with reference numeral # 1 are pulse signals generated for the first cylinder of the engine, and pulse signals with reference numeral # 2 for the second cylinder of the engine. It is a pulse signal that is generated. Further, in FIG. 3, # 1TDC and # 2TDC
Indicates the top dead center position of the first cylinder and the second cylinder (the rotation angle position of the crankshaft when the pistons of the first cylinder and the second cylinder reach the top dead center), and BTDC indicates the top dead center position. It indicates that the angle is measured on the advance side with respect to the reference. Further, ATDC indicates that the angle is measured on the retard side with reference to the top dead center.

In FIG. 3, the first pulse signals # 1Vs1 and # 2Vs1 for the first cylinder and the second cylinder are respectively
The reference position θ11 for the first cylinder and the second cylinder in which the crank angle θ of the internal combustion engine is set at a position sufficiently advanced from the top dead center positions # 1TDC and # 2TDC of the first and second cylinders. And the second pulse signal # 1 for the first cylinder and the second cylinder for the second cylinder, which occurs when the angles corresponding to θ12 and θ12 match.
Vs2 and # 2 Vs2 are generated when the crank angle θ coincides with the angles corresponding to the low speed ignition positions θ21 and θ22 set near the top dead center positions # 1TDC and # 2TDC of the first and second cylinders, respectively. is doing.

The first pulse signals # 1Vs1 and # 2Vs1 for the first cylinder and the second cylinder are used as reference signals for causing the MPU to detect the reference positions for the first cylinder and the second cylinder, respectively. These reference positions are used as positions for starting the process for measuring the ignition timing.

The second pulse signals # 1Vs2 and # 2Vs2 for the first cylinder and the second cylinder are supplied to the MPU as the first pulse signals.
It is used as a low speed ignition position signal for detecting the low speed ignition positions of the cylinder and the second cylinder. The low-time ignition position is set to a position suitable as a position corresponding to the ignition timing at the time of starting the engine and at low speed (for example, during idling).

In this example, the position where each pulse signal reaches the threshold value is the generation position of each pulse signal.

In the illustrated example, the reference positions .theta.11 and .theta.12 of the first cylinder and the second cylinder are set to the position of 75.degree. Before the top dead center of the first cylinder and the second cylinder, respectively. The low speed ignition positions .theta.21 and .theta.22 are set to 15 degrees before the top dead center position of the first and second cylinders, respectively. FIG. 2 is a stroke diagram of the engine showing the relationship between the top dead center position of each cylinder and the reference position and the ignition position at the low speed time point.

The first waveform shaping circuit 6 is a circuit for converting the first pulse signal Vs1 into a signal that can be recognized by the MPU, and includes transistors TR2 and TR3 and resistors R6 to R9.
And a capacitor C2 and diodes D7 and D8. The collector of the transistor TR3 is connected to the interrupt terminal INT1 of the MPU, and the cathode of the diode D8 is connected to the non-ground side terminal of the pulser coil 5.

In the first waveform shaping circuit 6, the transistor TR is used when the first pulse signal Vs1 is not generated.
Since 2 is on and transistor TR3 is off, the potential of the collector of transistor TR3 is at H level (high level). When the first pulse signal Vs1 above the threshold value is generated, the diode D7 and the resistor R
Current flows through 6 and diode D8, causing a forward voltage drop across diode D7 which reverse biases the base and emitter of transistor TR2. As a result, the transistor TR2 is turned off and the transistor TR3 is turned on, so that the potential of the collector of the transistor TR3 becomes L level (almost ground potential). Therefore, the potential of the interrupt terminal INT1 becomes H when the first pulse signal Vs1 reaches the threshold value.
Level to L level, and this potential drop is
Is recognized as a first interrupt signal by.

The second waveform shaping circuit 7 includes a transistor T
It is composed of R4, resistors R10 and R11, capacitor C3, and diode D9. The collector of the transistor TR4 is connected to the second interrupt terminal INT2 of the MPU, and the anode of the diode D9 is the non-grounded side terminal of the pulsar coil 5. It is connected to the.

In this second waveform shaping circuit, the second
When the pulse signal Vs2 is not generated, the transistor TR4 is turned off, and the potential of its collector is at the H level. When the second pulse signal Vs2 is generated,
Since the transistor TR4 is turned on, the potential of its collector becomes L level and the second interrupt terminal INT2
Potential drops from H level to L level. This decrease in potential is recognized by the MPU as a second interrupt signal.

As shown in FIG. 4, the first combustion pressure sensor 8A and the second combustion pressure sensor 8B have spark plugs PL1,
This is a seat-type combustion pressure sensor that is fitted to the threaded portion of PL2 and attached to the cylinder head 12 of the engine in a state where it is fastened together with the spark plug. This combustion pressure sensor uses a piezoelectric element as a transducer for converting pressure into an electric signal, and outputs a detection signal of an oscillating waveform whose level changes according to the fluctuation of the combustion pressure in the cylinder of the engine. When detonation occurs, the level of the detection signal output from the combustion pressure sensor becomes higher than that during normal combustion.Therefore, it is possible to detect the occurrence of detonation by comparing the magnitude of the output of this sensor with the judgment value. it can.
The peak value of the detection signal output by the combustion pressure sensor when detonation occurs reaches 20 V or more. The outputs of the combustion pressure sensors 8A and 8B are input to the first voltage conversion circuit 9A and the second voltage conversion circuit 9B through the lead wire 13.

The first voltage conversion circuit 9A comprises a series circuit of resistors R15 and R16 to which the output voltage of the power supply circuit 4 is applied,
A capacitor C4 connected across the resistor R16 and a resistor R4
A diode D11 whose cathode is connected to the connection point of 15 and R16, a non-grounded output terminal of the sensor 8A and a diode D
A resistor R17 connected between 11 and 11, a resistor R18 whose one end is connected to a connection point of the resistors R15 and R16, and a capacitor C4.
A diode D12 connected across a capacitor C4 and a resistor R15 so that the voltage across the
And the connection point of R16 and the non-ground side of the power supply circuit 4 (plus side)
The diode D12 and the diode D13 in the same direction are connected to the output terminal of the diode D12.

This voltage conversion circuit 9A is provided with the combustion pressure sensor 8
By dividing the output voltage of A by the voltage dividing circuit consisting of resistors R17 and R16, the output voltage of the combustion pressure sensor is lowered, and the DC voltage signal proportional to the peak value of the detection voltage output from the combustion pressure sensor 8A is reduced. Is output. This voltage conversion circuit 9A
Is the power supply circuit 4 when the output of the combustion pressure sensor 8A is zero.
A constant DC voltage corresponding to the voltage obtained by dividing the output voltage of the above with the resistors R15 and R16 is output as the minimum output voltage. When the detonation occurs, the maximum value of the voltage output by the voltage conversion circuit 9A is the voltage level (5
The resistance values of the resistors R15 to R18 are set so as to be lower than V).

The first peak hold circuit 10A has a first
Is a circuit for holding the peak value of the output voltage of the voltage conversion circuit 9A of the holding capacitor C5 and this capacitor C5.
To a peak value of the output voltage of the voltage conversion circuit 9A. In the illustrated example, the circuit for charging the hold capacitor C5 comprises a voltage follower circuit composed of an operational amplifier OP1 and a diode D15, and the combustion pressure sensor 8 is provided at both ends of the capacitor C5.
A voltage signal corresponding to the peak value of the detection signal output by A is generated.

The first discharge circuit 11A has a resistor R20 whose one end is connected to the non-grounded terminal of the hold capacitor C5.
And a resistor R21 connected between the other end of the resistor R20 and the ground to discharge the electric charge of the capacitor C5 with a constant discharge time constant.

The voltage signal obtained across the capacitor C5 of the first peak hold circuit 10A is the discharge circuit 11A.
A / D conversion input port A of MPU3 through the resistor R20
It is entered in 1.

In this example, the first voltage conversion circuit 9A, the first peak hold circuit 10A, and the first discharge circuit 11A.
Thus, the first peak value detection circuit that detects the peak value of the detection signal output from the first combustion pressure sensor 8A and outputs the voltage signal corresponding to the peak value is configured.

The second voltage conversion circuit 9B, the second peak hold circuit 10B and the second discharge circuit 11B are respectively the first voltage conversion circuit 9A and the first peak hold circuit 1.
0A and the first discharge circuit 11A, and the second voltage conversion circuit 9B, the second peak hold circuit 10B and the second discharge circuit 11B, the second combustion pressure sensor 8B A second detecting a peak value of the output detection signal and outputting a voltage signal corresponding to the peak value
The peak value detection circuit of is constructed. The output of this peak value detection circuit is input to the A / D conversion input port A2 of MPU3.

The voltage signals obtained from the first and second peak value detection circuits are converted into digital values by the A / D converter in MPU 3 and stored in the RAM in MPU.

The MPU 3 is set at a position advanced from the top dead center position of each cylinder of the internal combustion engine by executing a program stored in the ROM or an EEPROM (not shown) connected to the MPU. The crank angle range between the determined reference position and the top dead center position is set as an ignition processing section α (see FIG. 3) for performing processing for generating an ignition signal, and the ignition timing is calculated in this ignition processing section α. , Ignition control means for performing ignition processing including measurement of the calculated ignition timing and generation of an ignition signal.

This ignition control means corresponds to, for example, rotation speed calculation means for calculating the rotation speed of the internal combustion engine from the output pulse intervals of the pulser coil 5 and various control conditions such as throttle opening and cooling water temperature. Ignition timing calculating means for calculating the ignition timing, ignition timing measuring means for measuring the calculated ignition timing, and port P1 when the ignition timing is measured.
And an ignition signal generating means for generating an ignition signal by setting the potential of the L level to the L level (ground potential). The normal ignition timing is calculated in the form of an angle (ignition angle) from the reference position to the position corresponding to the ignition timing. Ignition timing measuring means,
From the calculated ignition angle and the rotation speed of the engine, the time required for the engine to rotate by the calculated ignition angle from the reference position is calculated as the ignition timer time, and the timer provided in the MPU is used as the ignition timer. Then, the timing operation of the ignition timer time by this ignition timer is started at the reference position. Timing at which the time measured by the ignition timer matches the calculated ignition timer time is detected as the ignition timing.

Although not shown, in the present embodiment, the output of the throttle sensor for detecting the opening of the throttle valve (throttle opening) Th and the output of the water temperature sensor for detecting the temperature T of the cooling water of the engine are provided. It is input to MPU3.

The MPU 3 calculates the ignition angle (angle from the reference position to the position corresponding to the ignition timing) Igt by the following formula.

Igt = Igt.X (Ne, Th, T) -Igt. F (1) where Igt.X (Ne, Th, T) is the engine speed Ne and the throttle opening Th. , Is a normal ignition angle calculated with respect to the engine coolant temperature T, and has a value suitable for obtaining the maximum output from the engine when detonation does not occur. Usually, this normal ignition angle Igt · X (Ne, Th, T) is an ignition angle calculation map (rotation speed Ne, throttle opening Th, engine coolant temperature T and ignition angle) stored in the ROM. It is obtained by performing an interpolation calculation on the data read from the table that gives the relation.

Further, in the equation (1), Igt · F is a normal ignition angle Igt · X for retarding the ignition timing when the detonation occurs or advancing the ignition timing when the detonation stops. (Ne, Th,
It is a correction value of the ignition angle that is added to T) or subtracted from the normal ignition angle. Here, it is assumed that the correction value Igt · F is always positive.

In this type of ignition device, normally, the reference position θ
By inputting the interrupt signal to the interrupt input terminal INT1 of the MPU 3 by the first pulse signal Vs1 at 11 and θ12, the first interrupt processing is performed. In this interrupt processing, after the rotation speed is calculated from the generation interval of the output pulse of the pulser coil 5, the time required for the crankshaft to rotate from the reference position to the position corresponding to the ignition timing at the calculated rotation speed is the ignition timer time. Calculate as. After that, it is determined whether the engine rotation speed is equal to or higher than the set rotation speed, and if the rotation speed is less than the set rotation speed (the crankshaft rotation speed fluctuation due to the change in the stroke of the engine is large, depending on the ignition timer If the calculated ignition timing cannot be accurately detected), the pulsar coil outputs the low-speed ignition position signal (second
Pulse signal Vs2) is generated, processing for permitting the generation of the ignition signal is performed, and then the first interrupt processing is ended. When the rotation speed is equal to or higher than the set rotation speed, processing for prohibiting the ignition signal from being generated by the low-speed ignition position signal and processing such as setting the calculated ignition timer time in the ignition timer are performed. After that, the first interrupt processing is ended.

The MPU 3 also causes the second interrupt processing to be performed when the second interrupt signal is given by the second pulse signal Vs2 generated by the pulsar coil. In this interrupt processing, when the ignition signal is allowed to be generated by the low-speed ignition position signal, the port P1 of the MPU is
The potential of is set to L level and an ignition signal is generated.

When the ignition timer has finished measuring the ignition timer time, the MPU 3 performs an ignition timer interrupt process to bring the potential of the port P1 to the L level and generate an ignition signal.

The interrupt processing will be described later in more detail with reference to a flowchart.

In the current MPU, it takes about 0.5 msec to perform the calculation processing in the first interrupt processing started at the reference position, such as the calculation of the rotation speed and the calculation of the ignition timer time. Therefore, for example, the engine rotation speed is 10,000
If it is 0 rpm, the MPU 3 is performing the first interrupt process in a section of about 30 degrees (section of α1 shown in FIG. 3) from the position of BTDC 75 degrees (reference position) to the position of about BTDC 45 degrees. .

Further, the pulsar coil 5 is set to the first position when the engine is started and when the engine speed is low because the stroke change of the rotation speed is large and the ignition position cannot be accurately detected by the ignition timer.
Low-speed ignition position signals # 1Vs2 and # 2V for the respective cylinders at low-speed ignition positions θ21 and θ22 of the cylinder and the second cylinder
When s2 is generated, the interrupt signal obtained by waveform shaping of the second pulse signal Vs2 is input to the interrupt terminal INT2 to cause the MPU3 to perform the second interrupt process, and the potential of the port P1 is respectively processed by this interrupt process. Is set to the L level to generate the ignition signals of the first cylinder and the second cylinder.

If the ignition timing is retarded to the top dead center position, the ignition timing measurement operation is performed by the ignition timer until the top dead center of each cylinder. Therefore, in the two-cylinder two-cycle internal combustion engine, the section from the position of # 1BTDC75 degrees, which is the reference position of the first cylinder, to the position of # 1BTDC0 degrees, which is the top dead center position, and the reference position # 2BTDC75 of the second cylinder. It is necessary to secure a section from the position of 0 degrees to the position of # 2BTDC0, which is the top dead center position, as the ignition processing sections # 1α and # 2α for performing the processing (ignition processing) necessary for generating the ignition signal.
No other processing can be performed in these ignition processing sections. However, from # 1BTDC 0 degree to # 1ATDC
105 degree section and # 2 BTDC 0 degree to # 2 ATDC
Since the ignition process is not performed in the section of 105 degrees, it can be used as a section in which another process is performed.

On the other hand, according to the result of the experiment conducted by the inventor, the detonation is apt to occur in the two-cycle engine from about # 1ATDC15 degrees to # 1ATDC70.
Degree section # 1γ and approximately # 2 ATDC 15 degrees to # 2A
It became clear that it was the section # 2γ of TDC 70 degrees (see FIG. 2).

In the present invention, sections other than the ignition processing section (in the above example, the section of # 1β from # 1BTDC0 degrees to # 1ATDC105 degrees and the section of # 2BTDC0 degrees to # 2AT).
Focusing on the fact that processing other than ignition processing can be performed in the # 2β section up to DC 105 degrees) and that these sections include sections where detonation is likely to occur, the ignition processing sections # 1α and # 2α are In the subsequent constant sections # 1β and # 2β, a series of processes necessary for detection of detonation are performed as well as calculation of the ignition angle.

In the present invention, the combustion pressure sensors 8A and 8B which detect the combustion pressure in the cylinder of the internal combustion engine and output a detection signal exceeding a predetermined level when detonation occurs.
And a peak value detection circuit (9A to 11A and 9B to 11B) that detects the peak value of the detection signals output by these combustion pressure sensors and outputs a voltage signal corresponding to the peak value are provided as hardware circuits. At the same time, the voltage signals output from these peak value detection circuits are converted into digital values VD1.
And A / D conversion means for converting to VD2
The A / D converter is used, and further, the MPU 3 executes a predetermined program to form a unit for realizing various functions. FIG. 12 is a functional block diagram showing the configuration of the main part of the present invention including the function realizing means realized by the MPU.

In FIG. 12, 8A and 8B are the first and second combustion pressure sensors shown in FIG. 1, 20A and 20B are voltage conversion circuits 9A and 9B, peak hold circuits 10A and 10B, and discharge circuits 11A and 11B, respectively. And first and second peak value detection circuits for detecting the peak value of the detection signals output by the combustion pressure sensors 8A and 8B and outputting a voltage signal corresponding to the peak value, 21A and 21B. Is a peak value detection circuit 20A and 2
0B outputs the voltage signal as digital values VD1 and VD2
The A / D converting means 22 for converting into a section is a section # 1β and # 2β of a constant crank angle range delayed from the top dead center position.
Combustion pressure digital value reading means for repeatedly reading the digital values VD1 and VD2 at 23, and 23 for the digital value VD1
And VD2 are compared with the determination values VX1 and VX2 for determining the presence or absence of detonation, and the detonation detection means for detecting that detonation has occurred when the digital value exceeds the determination value, 24 is set. The ignition timing calculated by the ignition control means when the number of times the detonation detecting means detects the occurrence of detonation within the set retarding condition determination time is equal to or greater than the set number of retarding determinations. If the number of times the detonation detecting means detects detonation within the set advance condition determination time is less than or equal to the set advance determination number or zero, the ignition timing is advanced and ignition is performed. The detonation suppressing ignition timing control means controls the ignition timing so as to cancel the correction to the retard side of the timing.

MP the A / D conversion means 21A and 21B.
If realized by the A / D converter built in U3, A
The time (conversion speed) required for / D conversion is about 10 μsec. On the other hand, when detonation occurs, the cycle of vibration of the detection signals output by the combustion pressure sensors 8A and 8B is several μs.
This is the order of c. Therefore, it is not possible to directly input the detection signal output of the combustion pressure sensor to the A / D conversion input port and A / D convert the peak value of the detection signal.

Therefore, in the present embodiment, a peak value detection circuit using the peak hold circuits 10A and 10B is provided, and the peak value of the voltage corresponding to the output voltage of the combustion pressure sensor is held by these circuits, whereby combustion is performed. The detection signal outputs of the pressure sensors 8A and 8B are converted into voltage signals with a cycle of several 100 μsec, and these voltage signals are respectively
By inputting to the A / D conversion input ports A1 and A2, the A / D conversion can be performed without any trouble.

In the detonation detecting means 23, the digital values VD1 and VD2 corresponding to the peak values of the detection signals of the combustion pressure sensors 8A and 8B thus obtained are stored in the ROM.
Alternatively, comparing with the judgment values VX1 and VX2 stored in the EEPROM, when the digital value VD1 corresponding to the peak value of the detection signal of the combustion pressure sensor 8A of the first cylinder is larger than the judgment value VX1, the first cylinder Detects that detonation has occurred, and detects that detonation has occurred in the second cylinder when the digital value VD2 corresponding to the peak value of the detection signal of the combustion pressure sensor 8B for the second cylinder is larger than the judgment value VX2. To do.

In this embodiment, in order to detect that the condition for retarding the ignition timing is satisfied in the detonation suppressing ignition timing control means 24, one counter in the MPU 3 is set to the first detonation counter ( The first timer (delay condition determination time measurement timer) 26 for measuring the delay condition determination time is used as the delay condition detection detonation counter) 25.
Used as. The first detonation counter 25 detects the number of occurrences of detonation, and the first timer 26 measures the retarding condition determination time Bsec for determining whether or not the condition for retarding the ignition timing is satisfied. . The first timer 26 is reset when the time measured by the timer exceeds the determination time Bsec and when the count value of the first detonation counter 25 reaches the set value A. And within the time of Bsec (for example, 1 sec), A
When the number of times (for example, once) detonation is detected, the ignition timing correction value is added with the set retard amount C degree, so that the ignition timing is set with the retard amount C degree (for example, 1).
Angle).

For example, 1 is added to the count value of the first detonation counter 25 when detonation is detected in either the first cylinder or the second cylinder while the crankshaft rotates 1/2. Even when it is detected that detonation occurs twice or more in each cylinder while the crankshaft rotates 1/2, the count value of the first detonation counter is incremented by one.

First detonation detection counter 25
The number of occurrences of detonation counted by
When it reaches (for example, once), the ignition angle correction value Ig
C degree is added to t · F to reset the first detonation detection counter and at the same time reset the first timer 26. The first timer is also reset when the measured time reaches the judgment time Bsec (for example, 1 sec).

By these operations, the count value of the first detonation counter 25 becomes A before the time measured by the first timer 26 reaches the first determination time Bsec.
When the number of times reaches, the set value C is added to the ignition angle correction value Igt · F.
Since the degree is added, the ignition timing is corrected to the retard side by C degree (for example, 1 degree). The retardation of the ignition timing suppresses detonation.

In the present embodiment, the MPU 3 is also used to detect that the condition for advancing the ignition timing is satisfied in the detonation suppressing ignition timing control means 24.
One of the other counters is used as a second detonation counter (detonation counter for advancing condition detection) 27, and the other one timer is used as a second timer (advancing condition for measuring advancing condition determination time. It is used as a judgment time measuring timer) 28. Then, the second detonation counter 27 detects the number of times detonation occurs, and the second timer 28 determines the advance condition determination time Esec for determining whether or not the condition for advancing the ignition timing is satisfied. measure. The second timer is reset when the determination time Esec has elapsed. Then, when the number of times of detonation detected within the time of Esec (for example, 3 sec) is D (for example, 0) or less, the ignition timing is advanced by the set advance amount F degree (for example, 1 degree).

For example, when detonation is detected in either the first cylinder or the second cylinder while the crankshaft is rotating ½, 1 is added to the count value of the second detonation counter 27. Even if detonation is detected twice or more in each cylinder while the crankshaft makes one-half rotation, the count value of the second detonation counter is incremented by one.

When the number of occurrences of detonation counted by the second detonation counter 27 is equal to or less than the set value D (for example, D = 0) when the second timer 28 reaches the determination time Esec (for example, 3 seconds). , The set value F is subtracted from the ignition angle correction value Igt · F to reset the second detonation detection counter 27 and, at the same time, reset the second timer 28.

When such control is performed, the count value of the second detonation counter 27 becomes equal to or less than the set value D (for example, 0) when the time measured by the second timer 28 reaches the judgment time Esec. In this case, F degree is subtracted from the ignition angle correction value Igt · F, and the ignition timing is advanced by F degree (for example, 1 degree).

As described above, in the present invention, the number of times detonation occurs is counted, the determination time is measured, and ignition is performed when it is detected that a predetermined number of detonations occur within the predetermined determination time. The ignition timing of the engine is corrected to the retard side by increasing the angle correction value by the set value. As a result, detonation is suppressed, so that detonation is not detected or the number of times it is detected is reduced.

When the number of times of detonation counted during the predetermined determination time is less than the predetermined number (including 0 times), the ignition timing is advanced by decreasing the correction value of the ignition angle by the set value. Angle to cancel the correction of the ignition timing to the retard side.

When such control is performed, the ignition timing is retarded when detonation occurs and the detonation is suppressed, and as soon as the detonation disappears, the ignition timing is advanced and the ignition timing retard is released. Because
It is possible to suppress the generation of detonation without sacrificing the output of the engine.

FIG. 5 is an explanatory view showing an example of detonation suppressing ignition timing control performed by the ignition device according to the present invention. FIG. 5A shows the ignition timing, and FIG. 5B shows the count value of the detonation counter. Yes, the horizontal axis represents time t.

In this example, the set value A of the number of times of detonation occurrence that establishes the condition for retarding the ignition timing is set to 4, and the condition for advancing the ignition timing (releasing the retardation of the ignition timing) is established. The set value D of the number of times of detonation occurrence is set to 0. Also, the retardation amounts C and F are both 1
I have a degree.

In the example shown in FIG. 5, the ignition timing is set to BTDC.
At 20 degrees, the number of times of detonation has reached the set value 4 within the B time while operating, so the ignition timing at the ignition timing at time t1 is delayed by C degrees (= 1 degree) to BTDC 19 degrees. . Next, since the number of times of detonation measured within the time B was 1, the first judgment time measuring timer was reset at the time t2, but thereafter, the number of times of detonation reached the set value 4 within the time B. Therefore, the ignition timing is retarded again by 1 degree at the ignition timing at time t3 to set the ignition timing to 18 degrees BTDC. After that, since the number of times detonation occurred was 0 during the elapse of the determination time E, the ignition timing is advanced by 1 degree at time t4 to set the ignition timing to 19 degrees BTDC.

In order to realize each means shown in FIG. 12, M
A flowchart showing an example of the algorithm of the program executed by the PU is shown in FIGS. 6 to 10.

FIGS. 6 and 7 show the main routine, and FIG. 8 shows that the pulser coil has the first pulse signal (reference signal) # 1.
The first interrupt routine executed when Vs1 and # 2Vs1 are generated is shown. 9 shows a second interrupt routine executed when the pulser coil generates the second pulse signals # 1Vs2, # 2Vs2, and FIG. 10 shows an ignition timer executed when the ignition timer measures the ignition timer time. The interrupt routine is shown.

In these routines, in order to determine whether or not a predetermined process is executed, whether or not detonation is detected, the crank angle range at each moment, and the like, flags 1 to 5 are determined.
Is used. The functions of these flags are summarized below.

Flag 1: First pulse generated by pulsar coil 5
Is a flag for determining whether the first interrupt processing by the pulse signal Vs1 has been performed, and is set to "1" when the first interrupt processing is completed.

Flag 2: A flag for storing whether or not detonation has occurred in the first cylinder. The digital value VD1 corresponding to the peak value of the detection signal of the combustion pressure sensor 8A for the first cylinder is the judgment value VX1. "1" when exceeding
Becomes

Flag 3: A flag for storing whether or not detonation has occurred in the second cylinder. The digital value VD2 corresponding to the peak value of the detection signal of the combustion pressure sensor 8B for the second cylinder is the judgment value VX2. "1" when exceeding
Becomes

Flag 4: When the ignition is performed at the calculated ignition timing, it is "1" from the generation positions (reference positions) θ11, θ12 of the first pulse signals # 1Vs1 and # 2Vs1 to the ignition position.

Flag 5: First pulse signal # 1Vs1, #
The second pulse signals # 1Vs2, # 2 from the generation position of 2Vs1
It is a section "1" up to the Vs2 generation position.

In the flowcharts shown in FIGS. 6 to 10, detonation counters 1 and 2 mean first and second detonation counters 25 and 27, respectively, and timers 1 and 2 are first and second timers 26, respectively. And 28 are meant.

When the ignition device is turned on, first, as shown in FIG.
And the main routine shown in FIG. 7 is started. In this main routine, first, in step 1 of FIG. 6, each part is initialized (initialized), and then in step 2, it is determined whether or not flag 1 is "1", and as a result, flag 1 is "1". At this time (when the first interrupt process of FIG. 8 is completed), the routine proceeds to step 3 to calculate the normal ignition angle Igt · X (Ne, Th, T). This calculation is performed by the map calculation described above. Next, in step 4, it is determined whether or not the flag 2 or 3 is "1". If the flag 2 or 3 is "1", the process proceeds to step 5 and the count value of the first detonation counter 25 is set. Increment, and in step 6, the count value of the second detonation counter 27 is incremented.
Next, in Step 7, the flags 2 and 3 are set to "0", and
Go to step 8 of. In this step 8, it is determined whether the count value of the first detonation counter 25 is A or more. If the result of this determination is that the count value is greater than or equal to A, the routine proceeds to step 9, where the ignition angle correction value Ig
The set value C is added to t · F, and in step 10, the first detonation counter 25 and the first timer 26 are reset.

Next, in step 11, the second timer 2
It is determined whether the measured value of 8 exceeds Esec. If the measured value exceeds Esec, the process proceeds to step 12 and the second timer 28 is reset. Next, in step 13, it is determined whether or not the count value of the second detonation counter 27 is less than or equal to the set value D (≧ 0). If the count value is less than or equal to D, in step 14, the second
Reset the detonation counter of. Next, at step 15, the set value F is subtracted from the ignition angle correction value Igt · F, and at step 16, the ignition angle Igt = Igt
After calculating X (Ne, Th, T) -Igt · F, the flag 1 is reset in step 17 (= 0) and the process returns to step 2 in FIG.

When it is determined in step 8 of FIG. 7 that the count value of the first detonation counter is less than A, the process proceeds to step 18 and the time measured by the first timer 26 exceeds Bsec. It is determined whether or not this time exceeds Bsec, and the routine proceeds to step 19, where the first timer 26 is reset. Then in step 20, reset the first detonation counter,
Go to step 11 above. When the time measured by the first timer 26 is Bsec or less in step 18, nothing is done and the process proceeds to step 11.

In step 11, the second timer 2
When the measured value of 8 is equal to or less than Esec, the process proceeds to step 16 to calculate the ignition angle, and in step 13, the second
When the count value of the detonation counter 27 of 6 exceeds D, the second detonation counter 27 is reset in step 21 and the process proceeds to step 16.

If it is determined in step 2 of FIG. 6 that flag 1 is not "1", then step 2
At step 2, it is determined whether the flag 4 set when the ignition timer time is set to 1 in the first interrupt routine described later is "1", and the flag 4 is set to "1". If so, do nothing and return to step 2. When it is determined in step 22 that the flag 4 is "0", the process proceeds to step 23 and the first
It is determined whether or not the flag 5 set in the interrupt routine of 1 is "1", and when the flag 5 is "1", nothing is done and the process proceeds to step 2. When it is determined in step 23 that the flag 5 is "0" (the crankshaft is from BTDC 0 degrees of each cylinder to ATDC 10
(In the range of 5 degrees), proceed to step 24 to read the digital value VD1 and read the read digital value VD1.
1 is compared with the judgment value VX1 for judging the occurrence of detonation. As a result, when VD1> VX1 (when it is determined that detonation is occurring in the first cylinder), the routine proceeds to step 25, where flag 2 is set to "1".
Set to. Next, the routine proceeds to step 26, where the digital value VD2 is read, the read digital value VD2 is compared with the judgment value VX2, and when VD2> VX2 (when it is judged that detonation has occurred in the second cylinder), After proceeding to 27 and setting the flag 3 to "1", the routine proceeds to step 2.

When it is determined in step 24 that VD1 ≤ VX1 (when it is determined that detonation does not occur in the first cylinder), the process proceeds to step 26, and when it is determined in step 26 that VD2 ≤ VX2 If it is determined that detonation has not occurred in the second cylinder, the process proceeds to step 2.

When the pulsar coil 5 generates the first pulse signal, the interrupt routine (first interrupt process) of FIG. 8 is executed. In this interrupt processing, in step 1, the difference between the time when the current interrupt is applied and the time when the previous interrupt is applied is detected as the time T required for one revolution of the crankshaft. Then, in step 2, the engine speed Ne (= 6 × 10
⁷ / T) is calculated. Next, at step 3, at the calculated rotation speed Ne, the time T'required for the crankshaft to rotate from the reference position to the position (ignition position) corresponding to the ignition timing is calculated by the following formula.

T ′ = (75−Igt) × (T / 360) (2) Next, in step 4, it is determined whether the rotation speed Ne is lower than a set value (1000 rpm in the illustrated example), and the rotation speed is determined. When is lower than the set value, the routine proceeds to step 5, where the hard ignition flag is set to "1". Here, hard ignition means that an ignition signal is generated at a position where a signal generated by hardware is generated to perform an ignition operation. In the present embodiment, the pulsar coil 5 generates a second pulse signal. Ignition that is performed when you do is called hard ignition. After setting the hard ignition flag, the flag 5 is set to "1" in step 6, the flag 1 is set to "1" in step 7, and the process returns to the main routine.

If it is determined in step 4 of FIG. 8 that the rotation speed is 1000 rpm or more, the process proceeds to step 8 to reset the hard ignition flag, and in step 9, the ignition timer time T'is set in the ignition timer. set. Also, flag 4 is set to "1" in step 10, and flag 5 is set in steps 11 and 12, respectively.
After setting the flag 1 to "1", the process returns to the main routine.

The MPU 3 also receives the second interrupt signal by the second pulse signal Vs2 generated by the pulsar coil, and the interrupt routine of FIG. 9 (second interrupt processing).
To execute. In this interrupt processing, first, the flag 5 is set to "0" in step 1, and it is determined in step 2 whether the hard ignition flag is "1". As a result, when the hard ignition flag is set to "1", an ignition signal is generated in step 3 (potential of port P1 is set to L level), and the process returns to the main routine. When it is determined in step 2 that the hard ignition flag is "0", nothing is done and the process returns to the main routine.

The MPU 3 also executes the ignition timer interrupt routine of FIG. 10 when the ignition timer measures the ignition timer time T '. Step 1 in this interrupt routine
At, it is determined whether the flag 4 is "1", and if the result is that the flag 4 is "1", an ignition signal is generated in step 2. Next, in step 3, the flag 4 is set to "0" and the process returns to the main routine. When it is determined in step 1 that the flag 4 is "0" (when the ignition timer time is not set in the ignition timer), nothing is done and the process returns to the main routine.

When the algorithm shown in FIGS. 6 to 10 is followed, the rotation speed detecting means for detecting the rotation speed of the engine from the generation interval of the output pulse of the pulser coil is constituted by steps 1 and 2 of FIG. In step 3, the ignition angle calculation means for calculating the angle from the reference position of the crankshaft to the position corresponding to the ignition timing as the ignition angle with respect to the control conditions within the rotation speed and the throttle opening is configured. Further, the ignition timer time calculating means for calculating the time required for the crankshaft to rotate from the reference position to the position corresponding to the ignition timing as the ignition timer time is constituted by step 3 in FIG. 8, and steps 9 and 10 in FIG. By the interruption processing of 1, the ignition timing measuring means for starting the measurement of the ignition timing from the reference position and generating the ignition signal when the ignition timing is measured is configured. Also, step 5 in FIG.
9 and the interrupt process of FIG. 9, low-speed ignition signal generating means for generating an ignition signal at the position where the second pulse signal is generated when the engine is started and at low speed is configured. , Ignition timer time calculation means,
An ignition signal is generated in the crank angle range between the reference position and the top dead center position set at a position advanced from the top dead center position of the internal combustion engine by the ignition timing measuring means and the low speed ignition signal generating means. As the ignition processing section for performing the processing for controlling the ignition timing, ignition control means for performing processing including calculation of ignition timing in the ignition processing section, measurement of the calculated ignition timing, and generation of an ignition signal is configured.

In the main routine of FIG. 6, a step of a constant crank angle range delayed from the top dead center position by the process of reading the digital value obtained by the A / D conversion means when executing steps 24 to 26. Thus, the combustion pressure digital value reading means 22 for repeatedly reading the digital value is realized.

Furthermore, when the digital values exceed the judgment value by comparing the digital values VD1 and VD2 with the judgment values VX1 and VX2 for judging the occurrence of detonation in steps 24 to 27 of FIG. The detonation detecting means 23 for detecting the occurrence of the detonation is formed.

Further, by the steps 4 to 7 of FIG. 6 and the steps of FIG. 7, the number of times the detonation detecting means detects the occurrence of detonation within the set retard condition judgment time B is set. When it is A or more, the ignition timing calculated by the ignition control means is retarded by a predetermined retardation amount C, and the number of times the detonation detection means detects detonation within the set advance condition determination time E is set. The detonation suppressing ignition timing control means 24 is configured to control the ignition timing so as to advance the ignition timing by a predetermined advance amount F when it is less than or equal to the advanced angle determination count D or zero.

In the above example, the peak value detection circuit is constructed by using the peak hold circuits 10A and 10B, but a known sample hold circuit may be used instead of the peak hold circuit. This sample hold circuit is a circuit for charging the hold capacitor to the peak value of the output voltage of the voltage conversion circuit every time a sample signal is given from the hold capacitor and MPU. In this case, the combustion pressure digital value reading means is the internal combustion engine. It is configured to repeatedly apply the sample signal to the sample hold circuit when the crank angle is out of the ignition processing section.
Since the sample hold circuit itself is known, a detailed description of its circuit configuration will be omitted.

In the above example, the peak hold circuit 10A
Although the discharge circuits 11A and 11B for discharging the hold capacitors of 10 and 10B with a constant time constant are provided, the discharge circuits may be replaced with a reset circuit to discharge the hold capacitors in response to a command from the MPU 3.

FIG. 11 shows an example of the configuration in which a reset circuit for the hold capacitor is provided. In this example, the hold capacitor C of the peak hold circuit 10A is used.
Reset switch 3 that can turn on and off the charge of 5
A reset circuit 30A for discharging through 0a is provided. The illustrated reset switch 30a comprises an NPN transistor TR5 whose emitter is grounded and whose collector is connected to the non-grounded side terminal of the hold capacitor C5 through a resistor R30. The base of the transistor TR5 is MPU.
Connected to a port B1 of the resistor through a resistor R31. A resistor R32 is connected between the base and emitter of the transistor TR5, and the non-ground side terminal of the hold capacitor C5 is resistor R.
It is connected to A / D conversion input port A1 through 20.

In this case, by causing the MPU to execute a predetermined program, the port B of the MPU is completed until the A / D conversion of the voltage signal by the A / D conversion means 21A is completed.
The potential of 1 is maintained at L level (low level or zero level) and the reset switch 30a is kept in the off state, and the A / D
After the conversion is completed, a reset switch control means for controlling the reset switch 30a so that the potential of the port B1 of the MPU is set to H level (high level) and the reset switch 30a is turned on is configured.

Although FIG. 11 shows only the reset circuit 30A provided for the first peak hold circuit 10A, the second peak hold circuit 10B is also controlled by the port B2 of the MPU. Reset circuit is provided. Reset switch control means is A / D
Until the conversion means 21B completes the A / D conversion of the voltage signal, the potential of the port B2 of the MPU is held at the L level to keep the reset switch for the second peak hold circuit 10B in the off state, After the D conversion is completed, the potential of the port B2 is set to H level and the reset switch is turned on. Although only the MPU 3 and the peak value detection circuit 20A are shown in FIG. 11, the configuration of the other parts is the same as that of the ignition device shown in FIG.

In the peak value detection circuit shown in FIG.
The time during which the terminal voltage of the hold capacitor holds the value corresponding to the peak value of the detection signal of the combustion pressure sensor is several tens.
It is on the order of 0 μsec. In this case, if the conversion speed of the A / D conversion means composed of the A / D converter built into the MPU is on the order of 10 μsec, the voltage signal obtained across the hold capacitor by performing A / D conversion without any problem. It is possible to obtain the digital value of the voltage value of
If the conversion speed of the conversion means is slow and is on the order of several hundreds of microseconds, it may not be possible to perform A / D conversion when interrupt processing overlaps, which may cause omission in detonation detection.

On the other hand, in the case where the reset circuit is provided as shown in FIG. 11, the A / D conversion by the A / D conversion means is performed.
Since the terminal voltage of the hold capacitor can be reliably held until the conversion is completed, detonation can be reliably detected even when the conversion speed of the A / D conversion means is slow.

In the case where the ignition timing is advanced to a timing at which detonation is likely to occur and the ignition timing is controlled so as to maximize the output of the engine while suppressing the detonation, the combustion pressure sensor should be used. If the detonation cannot be detected due to a failure or disconnection of the wiring from the combustion pressure sensor, the engine may continue to operate in the state where the detonation occurs, and the engine may be damaged. In order to prevent such a situation from occurring, the ignition timing calculated by the ignition control means when the digital value obtained from the A / D conversion means continues for a determination time set to be less than the threshold value It is preferable to add to the main routine a process for realizing a combustion pressure sensor abnormal point ignition timing control means for retarding the ignition timing by a predetermined retardation amount.

In the above example, the two-cylinder internal combustion engine is taken as an example, but the present invention can also be applied to a single-cylinder internal combustion engine and an internal combustion engine with more than three cylinders. Further, in the above example, the two-cycle engine is taken as an example, but the present invention can be applied to a four-cycle engine.

In the above example, the A / D converting means is realized by using the A / D converter incorporated in the MPU, but the A / D converting means is realized by using the external A / D converter. It may be configured.

In the above example, a capacitor discharge type circuit is used as the ignition circuit 2, but the present invention can also be applied to the case where a current cutoff type circuit is used.

[0124]

As described above, according to the present invention, the peak value detection circuit obtains a voltage signal corresponding to the peak value of the output signal of the combustion pressure sensor and converts the voltage signal into a digital value. By comparing this digital value with the judgment value prepared in advance by software, the detonation is detected, so the bandpass filter and comparator required in the conventional ignition device with the detonation suppression function are omitted. The cost can be reduced.

According to the present invention, the combustion pressure can be adjusted to absorb the variation in the characteristics of the detection circuit by changing the judgment value stored in the memory of the MPU. The adjustment work can be simplified as compared with the case of adjusting.

Furthermore, in the present invention, the ignition timing calculated by the ignition control means is set when the digital value obtained from the A / D conversion means continues for the determination time set to be less than the threshold value. When the combustion pressure sensor abnormal point ignition timing control means for retarding only the retard amount is provided, detonation can be detected when the combustion pressure sensor fails or the wiring from the combustion pressure sensor is broken. It can prevent the engine from being damaged when it runs out.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a hardware configuration example of an internal combustion engine ignition device according to the present invention.

FIG. 2 is a stroke diagram of a two-cycle two-cylinder internal combustion engine used in the embodiment of the present invention.

FIG. 3 is a waveform diagram showing an example of a pulse signal generated by a pulsar coil in a two-cycle two-cylinder internal combustion engine.

FIG. 4 is a sectional view showing a combustion pressure sensor used in the embodiment of the present invention.

FIG. 5 is a diagram for explaining an ignition timing control operation according to the present invention.

FIG. 6 is a flowchart showing a part of an algorithm of a main routine of a program executed by the MPU in the embodiment of the present invention.

FIG. 7 is a flowchart showing another part of the algorithm of the main routine of the program executed by the MPU in the embodiment of the present invention.

FIG. 8 is a flowchart showing an example of an algorithm of a first interrupt routine of a program executed by the MPU in the embodiment of the present invention.

FIG. 9 is a flowchart showing an example of an algorithm of a second interrupt routine of a program executed by the MPU in the embodiment of the present invention.

FIG. 10 is a flowchart showing an example of an algorithm of an ignition timer interrupt routine of a program executed by the MPU in the embodiment of the present invention.

FIG. 11 is a circuit diagram showing a configuration of a main part of another embodiment of the present invention.

FIG. 12 is a functional block diagram showing a configuration example of a main part of the embodiment of the present invention.

[Explanation of symbols]

1 ... Exciter coil, 2 ... Ignition coil, 3 ... MPU,
8A, 8B ... Combustion pressure sensor, 9A, 9B ... Voltage conversion circuit, 10A, 10B ... Peak hold circuit, 11A, 1
1B ... discharge circuit, 20A, 20B ... peak value detection circuit,
21A, 21B ... A / D converter, 22 ... Combustion pressure digital value reading means, 23 ... Detonation detection means, 24
... Detonation suppressing ignition timing control means, 30A ... reset circuit.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02P 13/00 303 F02P 5/15 DG01L 23/22 F term (reference) 2F055 AA21 BB19 CC55 DD20 EE23 FF28 3G019 AA03 AB01 BA02 BA07 CC15 DB07 DB13 DB16 DC07 FA05 FA06 GA01 GA02 GA05 GA09 GA11 GA15 KA28 KD17 3G022 AA02 BA07 DA01 DA02 EA01 FA02 FB03 GA01 GA02 GA05 GA08 GA09 GA15 3G084 AA02 BA17 EA01 EA02 EA04 EA07 EA11 EB08 EB24 FA10 FA19 FA20 FA21 FA33 FA38 FA39

Claims (6)

[Claims] 1. An ignition circuit for generating a high voltage for ignition when an ignition signal is given, a reference position set at a position advanced from a top dead center position of an internal combustion engine, and the top dead center position. Between the crank angle range and the crank angle range as an ignition processing section for performing the processing for generating the ignition signal, processing including calculation of ignition timing in the ignition processing section, measurement of the calculated ignition timing, and generation of the ignition signal. In an ignition device for an internal combustion engine, which comprises an MPU that constitutes an ignition control means for performing a combustion pressure sensor for detecting combustion pressure in a cylinder of the internal combustion engine and outputting a detection signal exceeding a predetermined level when detonation occurs. A peak value detection circuit that detects a peak value of a detection signal output by the combustion pressure sensor and outputs a voltage signal corresponding to the peak value; and a voltage signal output by the peak value detection circuit. A / D conversion means for converting into a digital value, combustion pressure digital value reading means for repeatedly reading the digital value in a section of a constant crank angle range delayed from the top dead center position, and generation of detonation for the digital value. Detonation detecting means for detecting the occurrence of detonation when the digital value exceeds the judgment value, and the detonation within the set retarding condition judgment time. When the number of times the detection means detects the occurrence of detonation is equal to or more than the set number of retarded angle determinations, the ignition timing calculated by the ignition control means is retarded by the set retarded amount, and the set advance angle When the number of times the detonation detecting means detects the detonation within the condition determination time is less than or equal to the set number of advance angle determinations or zero. The ignition device for an internal combustion engine equipped with detonation inhibition ignition timing control means for controlling the ignition timing, a so as to only advance advance amount, which is set to the ignition timing. 2. The peak value detection circuit includes a voltage conversion circuit that lowers a voltage level of a detection signal output from the combustion pressure sensor to a level that can be input to the MPU, a hold capacitor, and the hold capacitor. A peak hold circuit having a circuit for charging the output voltage of the voltage conversion circuit to a peak value and a discharge circuit for discharging the hold capacitor with a constant time constant are provided, and the voltage signal is provided across the hold capacitor. The ignition device for an internal combustion engine according to claim 1, which is configured to generate. 3. The peak value detection circuit, a voltage conversion circuit that lowers the voltage value of the detection signal output by the combustion pressure sensor to a level close to a level that can be input to the MPU, a hold capacitor, and the hold capacitor A peak hold circuit having a circuit for charging the output voltage of the conversion circuit to a peak value; and a reset circuit configured to discharge the charge of the hold capacitor through a reset switch capable of on / off control. A voltage signal is generated by the A / D changing means and is configured to generate the voltage signal across the hold capacitor.
Reset switch control means for controlling the reset switch so that the reset switch is kept in the OFF state until the D conversion is completed, and the reset switch is turned on after the A / D conversion is completed. The ignition device for an internal combustion engine according to claim 1, further comprising: 4. The peak value detection circuit, a voltage conversion circuit that lowers the voltage level of the detection signal output from the combustion pressure sensor to a level that can be input to the MPU, a hold capacitor, and a sample signal from the MPU. And a sample and hold circuit having a circuit for charging the hold capacitor to the peak value of the output voltage of the voltage conversion circuit each time the combustion pressure digital value reading means is used. 2. The ignition device for an internal combustion engine according to claim 1, wherein the ignition device is configured to repeatedly apply a sample signal to the sample hold circuit when an angle is out of the ignition processing section. 5. A combustion pressure for retarding the ignition timing calculated by the ignition control means by a set retard amount when the state in which the digital value is less than a threshold value continues for a set determination time. The ignition device for an internal combustion engine according to any one of claims 1 to 4, further comprising ignition timing control means for abnormal sensor timing. 6. The voltage signal output from the peak value detection circuit is input to an A / D conversion input port provided in the MPU, and the A / D conversion means is an A / D conversion unit incorporated in the MPU. The ignition device for an internal combustion engine according to any one of claims 1 to 5, wherein A / D conversion of the voltage signal is performed by a heater.