JP3582423B2 - Internal combustion engine ignition device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an internal combustion engine. Ignition internal combustion engine It relates to an ignition device.
[0002]
[Prior art]
As an ignition device for igniting an internal combustion engine, a high voltage for ignition is induced in a secondary coil of an ignition coil by interrupting a primary current flowing through a primary coil of an ignition coil at an ignition position of the engine. A current interruption type device in which an engine is ignited by applying a pressure to a spark plug is often used.
[0003]
In a conventional ignition device of this type, a primary current control switch is connected in series to a primary coil of an ignition coil in which a secondary coil is connected to an ignition plug attached to a cylinder of an internal combustion engine. After the primary current control switch is turned on at an energization start position advanced from the ignition position of the internal combustion engine, a primary current flows from the DC power supply through the primary coil and the primary current control switch of the ignition coil, and then the ignition is performed. The primary current control switch is turned off at the position to cut off the primary current, thereby inducing a high voltage for ignition in the secondary coil of the ignition coil, and applying the high voltage for ignition to the ignition plug attached to the cylinder of the internal combustion engine. To generate a discharge to ignite the internal combustion engine.
[0004]
FIG. 8 shows an example of a conventional ignition device of this type. In FIG. 8, reference numeral 1 denotes an ignition coil having a primary coil 1a and a secondary coil 1b having one end commonly connected, and 2 denotes a primary current control switch. The primary current control switch 2 comprises a main transistor TR1 having a collector-emitter circuit connected in series to the primary coil 1a.
[0005]
Reference numeral 3 denotes a battery as an ignition power supply. The output voltage of the battery 3 is applied to both ends of a series circuit of a primary coil 1a and a primary current control switch 2 through a key switch 4.
[0006]
Reference numeral 5 denotes a power supply circuit to which the output voltage of the battery 3 is inputted through a diode D1. This power supply circuit outputs a constant DC voltage Vcc (5 V in the illustrated example) and a reset signal Vreset when the switch 4 is closed. .
[0007]
Reference numeral 6 denotes a CPU of the microcomputer. A power supply terminal of the microcomputer is supplied with a power supply voltage Vcc from the power supply circuit 5, and a reset terminal is supplied with a reset signal Vreset.
[0008]
Reference numeral 7 denotes a cutoff control switch including a cutoff control transistor TR2 and resistors R1 to R4. The collector and the emitter of the transistor TR2 are connected to the base and the emitter of the main transistor TR1, respectively. The base of the transistor TR2 is connected to the port P1 of the CPU through a resistor R2. When the potential of the boat P1 is set to a high level (non-grounded state), a base current is supplied to the transistor TR2 through the resistor R2. It has become.
[0009]
Reference numeral 8 denotes a signal generator including a rotor 8a that rotates synchronously with the crankshaft of the internal combustion engine and a stator 8b that detects a reluctor 8a1 provided on the rotor 8a and generates a pulse signal. The stator 8b has a well-known structure including an iron core having a magnetic pole portion at the tip facing the reluctor 8a1, a pulsar coil WP wound around the iron core, and a permanent magnet magnetically coupled to the iron core. When the leading edge and the trailing edge of the reluctor 8a1 in the rotational direction are detected, pulse signals Vs1 and Vs2 are generated from the pulser coil wp. When the waveforms of the pulse signals Vs1 and Vs2 generated by the pulsar coil are shown with respect to the rotation angle θ of the crankshaft, the waveforms are as shown in FIG. 9 (A), from the generation of the pulse signal Vs1 to the generation of the pulse signal Vs2. The angle is the polar arc angle (reactor width) θr of the reluctor 8a1. The pulse signals Vs1 and Vs2 are given to the CPU 6 through the waveform shaping circuit 9.
[0010]
In this example, a primary current control switch 2, a cutoff control switch 7, a power supply circuit 5, a diode D1, a CPU 6, and a waveform shaping circuit 9 are arranged in a common exterior and an ECU (electronic control unit) is provided. ) Is configured.
[0011]
The CPU 6 calculates the rotation speed [rpm] of the engine from the generation interval (time) of the pulse signals Vs1 and Vs2, and determines the ignition position of the engine and the energization start position (the current is supplied to the primary coil of the ignition coil) with respect to the calculated rotation speed. (Flowing start position).
[0012]
The CPU 6 also supplies a calculated energization start position and ignition position to an energization timer and an ignition timer (both timers for counting time by counting clock pulses) provided therein when the pulse signal Vs1 is generated. A numerical value is set, and measurement of the energization start position θa and the ignition position θi is started. When the energization timer completes counting the count value giving the energization start position θa (when the energization start position is detected), the potential of the port P1 is set to the ground potential, and the transistor TR2 is turned off.
[0013]
When the transistor TR2 is cut off, a base current is supplied from the battery 3 to the transistor TR1 through the diode D1 and the resistor R3, so that the transistor TR1 conducts, and the primary coil 1a of the ignition coil from the battery 3 and the collector emitter of the transistor TR1. A primary current i1 flows as shown in FIG.
[0014]
Next, the CPU sets the potential of the port P1 to a high level when the ignition timer completes counting of the count value giving the ignition position θi, thereby turning on the transistor TR2. When the transistor TR2 is turned on, the base current of the main transistor TR1 is bypassed from the transistor TR1, so that the transistor TR1 is cut off and the primary current i1 of the ignition coil is cut off as shown in FIG. 9B. Is done. As a result, a high voltage is induced in the primary coil 1a of the ignition coil so that the primary current that has been flowing until then continues to flow. This voltage is further raised to induce a high ignition voltage Vh (see FIG. 9C) in the secondary coil 1b of the ignition coil, and this high ignition voltage is applied to the ignition plug 10 attached to the cylinder of the engine. . As a result, spark discharge occurs in the ignition plug 10 and the engine is ignited. FIG. 9D shows the discharge current id flowing through the secondary coil 1b at this time.
[0015]
Here, assuming that the capacitance of the secondary side of the ignition coil 1 is C2, the spark voltage of the gap of the spark plug is Vs, the glow discharge current is Ig, the glow discharge voltage is Vg, and the discharge duration time is Td, the discharge energy W Is approximately given by the following equation.
[0016]
W = (C2 Vs ² + Vg Ig Td) / 2 (1)
The discharge duration Td is determined by the inductance (impedance) of the ignition coil, assuming that the discharge gap length of the spark plug is constant and C2, Vs, Vg and Ig are unchanged.
[0017]
FIGS. 10A to 10C respectively show the waveform of the primary current i1 in the conventional ignition device, the waveform of the ignition high voltage Vh induced in the secondary coil of the ignition coil, and the discharge flowing in the secondary coil of the ignition coil. The waveform of the current id is shown with respect to time t. In the figure, Vs is the spark voltage of the discharge gap of the spark plug, Vg is the glow discharge voltage, Ig is the glow discharge current, and Td is the discharge duration.
[0018]
In this type of ignition device, when the spark plug is new and the contacts forming the discharge gap of the spark plug are not worn out, as shown in FIG. 10, the discharge duration is long and high ignition performance can be obtained. However, as the wear of the contacts of the spark plug progresses and the gap length increases, the discharge duration time Td decreases, and the ignition performance decreases.
[0019]
[Problems to be solved by the invention]
2. Description of the Related Art An ignition device that ignites an internal combustion engine that drives a device that is continuously operated for a long time, such as a gas heat pump or an engine generator, is required to stably generate an ignition spark over a long period of time.
[0020]
However, in the current interruption type ignition device for an internal combustion engine, the discharge energy is large when the spark plug is new and the contact of the discharge gap is not consumed, and the discharge duration becomes longer than necessary. However, there is a problem in that the use of the spark plug causes the contact point of the spark plug to wear out, the duration of discharge to be shortened, and the ignition performance to deteriorate.
[0021]
SUMMARY OF THE INVENTION It is an object of the present invention to prevent a discharge duration from becoming unnecessarily long, suppress consumption of a contact of a spark plug, and stably generate an ignition spark over a long period of time. Shaped Internal combustion engine ignition device Is to provide.
[0022]
[Means for Solving the Problems]
In the present invention, A primary current control switch is connected in series to a primary coil of an ignition coil in which a secondary coil is connected to an ignition plug attached to a cylinder of the internal combustion engine, and is advanced from the ignition position of the internal combustion engine. The primary current control switch is turned on at the energization start position, so that the primary current flows from the DC power supply through the primary coil of the ignition coil and the primary current control switch, and then the primary current control switch is turned off at the ignition position. By interrupting the primary current, a high voltage for ignition is induced in the secondary coil of the ignition coil, and the high voltage for ignition is applied to a spark plug attached to a cylinder of the internal combustion engine to discharge with the spark plug. The ignition causes the internal combustion engine to ignite.
[0023]
In the present invention, after the primary current of the ignition coil is cut off at the ignition position, when the set discharge time has elapsed, the primary current control switch is turned on to flow current from the DC power supply to the primary coil of the ignition coil. Performs a discharge stop process that stops the discharge that occurred in the spark plug, stops the discharge that occurred in the spark plug, and shuts off the primary current control switch that was conducting while gradually increasing its internal resistance. Then, the primary current control switch is kept in the cut-off state until the next energization start position.
[0024]
As described above, after the primary current of the ignition coil is interrupted, the primary current control switch is turned on when the set discharge time has elapsed, and the current is passed from the DC power supply to the primary coil of the ignition coil to thereby cause the ignition plug When the discharge that has occurred in step (1) is stopped, the duration of the discharge can be limited, so that the duration of the discharge can be prevented from becoming unnecessarily long. Therefore, it is possible to prevent the discharge gap of the spark plug from being exhausted at an early stage and to reduce the ignition performance, and to maintain the high ignition performance for a long time to stably perform the continuous operation of the engine. .
[0025]
above When performing the ignition method, it is preferable to release the restriction on the discharge duration when the consumption of the spark plug has progressed to some extent.
[0026]
For this purpose, an integrating means for integrating the operating time or the number of ignitions of the internal combustion engine is provided, and when the integrated value obtained by the integrating means is equal to or less than a set value, the time from when the primary current of the ignition coil is cut off at the ignition position is determined. After the set discharge time has elapsed, the primary current control switch is turned on, and a current is passed from the DC power supply to the primary coil of the ignition coil to stop the discharge generated in the ignition plug. The primary current control switch is shifted from the conduction state to the interruption state while gradually increasing its internal resistance, and the primary current control switch is kept in the interruption state until the next energization start position, and the integrated value is set to the set value. If the ignition current exceeds the limit, the primary current control switch must be turned off at the ignition position to shut off the primary current of the ignition coil, and then the discharge stop process shall be performed. Ku, so as to hold the primary current control switch to the next energization start position to the blocking state.
[0027]
As described above, when the operating time or the number of ignitions of the internal combustion engine is integrated and the restriction on the discharge duration is released when the integrated value reaches the set value, the discharge gap of the spark plug is consumed to some extent. When the ignition performance is reduced, the discharge duration can be extended to recover the ignition performance, so that the operable time of the internal combustion engine can be further extended.
[0028]
Implement the above ignition method Of the present invention The igniter includes a DC voltage across a series circuit of an ignition coil, a main transistor having a collector-emitter circuit connected in series to a primary coil of the ignition coil, and a collector-emitter circuit of the primary coil and the main transistor. And an ignition control unit that controls the main transistor to be in a conductive state at an energization start position advanced from the ignition position of the internal combustion engine, and to shut off the main transistor at the ignition position. .
[0029]
According to the present invention, the ignition control unit includes an auxiliary transistor provided so as to allow a base current to flow from the DC power supply to the main transistor when in the conductive state, and a base current of the main transistor when in the conductive state. A shutoff control switch provided to bypass the main transistor to turn off the main transistor; an integrating means for integrating the operating time or the number of ignitions of the internal combustion engine; and a position advanced from the ignition position of the internal combustion engine. Auxiliary transistor driving means for turning on the auxiliary transistor when an energization start position defined in the above is detected, and a shutoff control switch which supplies a drive signal to a shutoff control switch when an ignition position of the internal combustion engine is detected. An ignition cut-off control switch driving means for turning on and off the internal combustion engine when the integrated value obtained from the integrating means is equal to or less than a set value. Discharge time measurement means for starting the measurement of the discharge time set in the discharge time measurement timer at the ignition position of the seki, and when the integrated value obtained from the integration means is equal to or less than the set value, the discharge time measurement means When the measurement is completed, the cutoff control switch is set to the cutoff state, and when the integrated value exceeds the set value, the cutoff control switch is set to the cutoff position at a position delayed from the position where the discharge time measuring means completes the measurement of the discharge time. A switch control means for shut-off control at the end of discharge, and a base time given to the auxiliary transistor from a position further delayed than a position at which the discharge time measurement timer completes the measurement of the discharge time. A configuration including auxiliary transistor cutoff control means for controlling the auxiliary transistor to be turned off at a position sufficiently advanced from the energization start position; That.
[0030]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows an example of the configuration of an internal combustion engine ignition device according to the present invention. In FIG. 1, the same reference numerals as in FIG. 8 denote the same parts as those in the conventional ignition device shown in FIG. It is.
[0031]
In FIG. 1, reference numeral 1 denotes an ignition coil having a primary coil 1a and a secondary coil 1b having one end commonly connected, and 2 denotes a primary current control switch composed of an NPN-type main transistor TR1 having an emitter grounded. The collector-emitter circuit is connected in series with the primary coil 1a of the ignition coil.
[0032]
Reference numeral 3 denotes a battery as an ignition power source. The output voltage of the battery 3 is applied to both ends of a series circuit of a primary coil 1a and a primary current control switch 2 through a key switch 4.
[0033]
Reference numeral 5 denotes a power supply circuit to which the output voltage of the battery 3 is input through the diode D1. Reference numeral 6 denotes a microcomputer CPU. A constant DC voltage Vcc obtained from the power supply circuit 5 is supplied to a power supply terminal of the CPU 6. The power supply circuit 5 also outputs a reset signal Vreset when the key switch 4 is closed. It is provided to a reset terminal of the CPU 6. The CPU 6 initializes each unit when a reset signal Vreset is given from the power supply circuit.
[0034]
Reference numeral 7 denotes an NPN-type cut-off control switch comprising a cut-off control transistor TR2 and resistors R1 to R4. The collector and the emitter of the transistor TR2 are connected to the base and the emitter of the main transistor TR1, respectively. The base of the transistor TR2 is connected to the port P1 of the CPU through the resistor R2. When the potential of the boat P1 is set to a high level (non-ground state), the base of the transistor TR2 is supplied to the transistor TR2 to generate a base current. TR2 is turned on.
[0035]
Reference numeral 8 denotes a signal generator provided for obtaining rotation information of the internal combustion engine. The signal generator includes a rotor 8a that rotates synchronously with a crankshaft of the internal combustion engine, and a rotation direction of a reluctor 8a1 provided on the rotor 8a. And a stator 8b for detecting the leading edge and the trailing edge of each of them to generate a first pulse signal Vs1 and a second pulse signal Vs2. The first and second pulse signals Vs1 and Vs2 obtained from the signal generator 8 are input to the CPU 6 through the waveform shaping circuit 9. In this example, the first pulse signal Vs1 at the reference position .theta.1 set at a position sufficiently advanced from the rotational angle position of the crankshaft corresponding to the top dead center of the engine (hereinafter simply referred to as "top dead center position"). And a signal generator 8 is provided to generate a second pulse signal Vs2 near the top dead center of the engine.
[0036]
The CPU 6 is provided with a timer and the like in addition to the ROM and the RAM. In the illustrated example, the EEPROM 11 is further connected to the CPU 6.
[0037]
The collector of an auxiliary transistor TR3 comprising a PNP transistor is connected to the base of the main transistor TR1 through a resistor R3, and the emitter of the transistor TR3 is connected to the cathode of a diode D1 whose anode is connected to the positive terminal of the battery 3 through a key switch 4. ing.
[0038]
The base of the auxiliary transistor TR3 is connected to the collector of the NPN transistor TR4 whose emitter is grounded through resistors R5 and R6, and a capacitor C1 is connected between the emitter of the transistor TR3 and the node between the resistors R5 and R6.
[0039]
The base of the transistor TR4 is connected to the port P2 of the CPU 6 through a resistor R7. Resistors R8 and R9 are connected between the base of the transistor TR4 and ground, and between the port P2 and ground, respectively.
[0040]
In the example shown in FIG. 1, a circuit for charging the capacitor C1 is constituted by the battery 3, the key switch 4, the diode D1, the capacitor C1, the resistor R6, the collector-emitter circuit of the transistor TR4, and the battery 3. When the transistor TR3 is turned off, the base current of the transistor TR3 is temporarily reduced to gradually turn off the transistor TR3 by the capacitor C1-emitter-base circuit of the transistor TR3, the resistor R5, and the capacitor C1. An auxiliary transistor cutoff control circuit is configured.
[0041]
In the ignition device shown in FIG. 1, before the primary coil of the ignition coil is energized, both the ports 1 and 2 of the CPU 6 are at the ground potential (state of “0”).
[0042]
When the crankshaft of the engine rotates, the signal generator 8 generates a first pulse signal Vs1 and a second pulse signal Vs2 as shown in FIG. The CPU 6 calculates the rotation speed [rpm] of the engine from the generation interval (time) of these pulse signals Vs1 and Vs2, and determines the power supply start position θa at which power supply to the primary coil of the ignition coil is started with respect to the calculated rotation speed. And the ignition position (position at which the primary current of the ignition coil is cut off) θi. These positions are calculated in the form of the time required for the engine to rotate from the reference position θ1 at which the first pulse signal Vs1 is generated to each position (count value of the clock pulse).
[0043]
The CPU 6 measures the energization start position θa and the ignition position θi by setting the calculated energization start position and ignition position calculated values in the energization timer and the ignition timer when the first pulse signal Vs1 is generated. To start. When the energization timer measures (detects) the energization start position .theta.a, the CPU sets the potential of the port P2 to a high level (state "1") to turn on the transistor TR4, thereby turning on the auxiliary transistor TR3. .
[0044]
When the transistor TR3 is turned on, the main transistor TR1 is turned on, so that a primary current i1 (FIG. 5B) flows from the battery 3 through the primary coil 1a of the ignition coil and the main transistor TR1. When the transistor TR4 is turned on, the capacitor C1 is charged to the polarity shown by the voltage of the battery 3.
[0045]
Next, the CPU 6 sets the potential of the port P1 to a high level (state of "1") while keeping the potential of the port P2 at a high level when the ignition timer measures the ignition position .theta.i, thereby turning on the transistor TR2. Then, the main transistor TR1 is turned off. When the main transistor TR1 is turned off, the primary current i1 of the ignition coil is cut off as shown in FIG. 5B, so that the ignition high voltage Vh (see FIG. 5C) is induced in the secondary coil 1b of the ignition coil. The ignition high voltage is applied to the ignition plug 10 attached to the cylinder of the engine. As a result, spark discharge occurs in the ignition plug 10 and the engine is ignited. At this time, a discharge current id flows through the secondary coil 1b of the ignition coil as shown in FIG.
[0046]
In the present invention, if the discharge duration at the time of ignition is limited to a set time Td1 shorter than the discharge duration Td (see FIG. 10) when the discharge state is naturally left, the energization timer is set at the ignition position. The time Td1 is set, and the measurement of the set time Td1 is started. Then, the potential of the port 1 of the CPU is set to the ground potential at the rotation angle position θb when the energization timer measures the set time Td1. As a result, the transistor TR2 is turned off, the main transistor TR1 is turned on again, and the power supply from the battery 3 to the primary coil of the ignition coil is restarted at the rotation angle position θb as shown in FIG. 5B. When the energization of the primary coil of the ignition coil is restarted, a voltage having a polarity preventing the increase of the primary current i1 is induced in the primary coil 1a, and this voltage is boosted and appears in the secondary coil 1b. Therefore, energization of the discharge current id flowing through the secondary coil 1b and the ignition plug 10 is prevented, and the discharge generated in the ignition plug 10 is stopped. By these operations, the discharge duration time is limited to the set time Td1. After the discharge at the spark plug is stopped in this manner, the potential of the port P2 of the CPU 6 is changed to the ground potential ("0") at the rotation angle position .theta.2 where the second pulse signal Vs2 generated by the signal generator is detected. State). When the potential of the port P2 of the CPU 6 is lowered, the transistor TR4 is turned off. At this time, the electric charge of the capacitor C1 is discharged through the space between the emitter and the base of the transistor TR3 and the resistor R5. Since this discharge current is gradually attenuated by a time constant determined by the capacitance of the capacitor C1 and the resistance of the resistor R5, the transistor TR3 is turned off while gradually increasing the internal resistance between its emitter and collector. Transition. Since the base current of the main transistor TR1 gradually decreases while the transistor TR3 shifts to the cutoff state, the main transistor TR1 shifts to the cutoff state while gradually increasing the internal resistance between its collector and emitter. Accordingly, the primary current i1 of the ignition coil is gradually reduced as shown in FIG. 5B, and the primary current i1 becomes zero without inducing a high voltage in the secondary coil of the ignition coil.
[0047]
FIGS. 6A to 6C schematically show enlarged waveforms of the primary current i1, the secondary voltage Vh and the secondary discharge current id of the ignition coil, respectively. In these figures, Vs denotes the ignition plug. , Is is a spark discharge current, Vg is a glow discharge voltage, and Ig is a glow discharge current.
[0048]
When the discharge duration is limited to the set time Td1 (<Td) as in the present invention, compared to the case where the discharge time is not limited, the discharge corresponding to the area of the hatched portion in FIG. Energy is reduced. As a result, wear of the contacts forming the discharge gap of the spark plug is suppressed, and the life of the spark plug is extended.
[0049]
When the ignition method of the present invention is applied, it is preferable to release the restriction on the discharge duration time when the wear of the contacts of the ignition plug has advanced considerably. For this purpose, for example, an integrating means for integrating the number of ignitions or the operating time (operating time) is provided, and the integrated value of the number of ignitions or the operating time by the integrating means is stored in the EEPROM 11, and the integrated value is set to a set value. Is exceeded, it is determined that the wear of the contacts of the ignition plug is considerably advanced, and the restriction on the discharge duration time may be released. In this case, the set value of the number of ignitions or the integrated value of the operation time is experimentally determined.
[0050]
FIGS. 2 to 4 are flowcharts showing an algorithm of a main part of a program executed by the CPU 6 in the above-described ignition device. FIG. 2 shows an interrupt routine executed when the ignition timer measures the calculated ignition position, and FIG. 3 shows an interrupt routine executed when the energization timer measures the set value Td1 of the discharge duration. ing. FIG. 4 shows an interrupt routine executed when the signal generator generates the second pulse signal Vs2.
[0051]
When the ignition timer measures the ignition position at the angle θi shown in FIG. 5 or FIG. 6, step 1 in FIG. 2 is executed, and the integrated value Ts of the operation time of the internal combustion engine is compared with the set value α. As a result, when the integrated value Ts is equal to or smaller than the set value α (when the contact of the spark plug has not been consumed so much), the process proceeds to step 2 and the set value Td1 of the discharge duration is set in the energization timer. The timer starts measuring Td1. Next, at step 3, the port P1 of the CPU is changed from "0" to "1", and the process returns to the main routine (not shown).
[0052]
When the energization timer measures the set value Td1 of the discharge continuation time at the position of the angle θb in FIG. 5 or 6, the interrupt routine in FIG. 3 is executed. In this interrupt routine, the port P1 of the CPU is changed from "1" to "0", and then the process returns to the main routine.
[0053]
Thereafter, when the signal generator generates the second pulse signal Vs2 at the position of the angle θ2 in FIG. 5 or FIG. 6, the interrupt routine in FIG. 4 is executed, and the port P1 of the CPU changes from “1” to “0”. Let me do.
[0054]
In the above example, the position θ2 at which the second pulse signal Vs2 is generated depends on the secondary discharge current of the ignition coil when the ignition is performed at the most retarded position near the top dead center position of the engine at a low speed of the engine. Is set to a position where the image disappears naturally or a position further retarded from that position.
[0055]
In a main routine (not shown), the calculation of the rotation speed of the internal combustion engine, the calculation of the ignition position with respect to the calculated rotation speed, the calculation of the energization start position, and the like are performed.
[0056]
In the above example, the process of setting the potential of the port P2 to a high level when the energization timer detects the energization start position θa, and the energization determined at a position advanced from the ignition position of the internal combustion engine by the transistor TR4. Auxiliary transistor driving means for turning on the auxiliary transistor TR3 when the start position is detected is realized.
[0057]
When the ignition timer measures the ignition position, the process of setting the potential of the port P1 of the CPU to a high level state (step 3 in FIG. 2) allows the shut-off control switch 7 to detect the ignition position of the internal combustion engine. The ignition-time cut-off control switch driving means for supplying a drive signal to the switch to turn on the cut-off control switch is realized.
[0058]
Further, according to an energization timer provided in the CPU and steps 1 and 2 in FIG. 2, when the integrated value obtained from the integrating means is equal to or smaller than the set value, the discharge time set at the ignition position of the internal combustion engine is reduced. A discharge time measuring means for starting the measurement is realized.
[0059]
When the integrated value obtained from the integrating means is equal to or less than the set value, the discharging time measuring means measures the set discharging time by the steps 1 and 2 of FIG. 2 and the interrupt routine of FIGS. When completed, the cutoff control switch is turned off, and when the integrated value exceeds the set value, the cutoff control switch is cut off at a position later than the position where the discharge time measuring means completes the set discharge time measurement. A switch control means for shutoff control at the end of discharge to be in a state is realized.
[0060]
Further, the interrupt routine shown in FIG. 4, the capacitor C1 and its discharge circuit, and the discharge time measurement timer complete the measurement of the discharge time set by the discharge time measurement timer (the position .theta.b in FIG. 5). Thus, the auxiliary transistor cutoff control means for gradually reducing the base current applied to the auxiliary transistor TR3 and turning off the auxiliary transistor at a position sufficiently advanced from the energization start position is realized.
[0061]
In the above example, after the set value Td1 of the discharge duration is measured, when the second pulse signal Vs2 is generated at the position of the angle θ2, the potential of the port 2 of the CPU is lowered to gradually turn on the auxiliary transistor TR3. Although the state is shifted to the cutoff state, the potential of the port 2 of the CPU is reduced when the timer without the CPU measures a predetermined time (for example, 1 msec) after the set value Td1 of the discharge duration time is measured. Thus, the auxiliary transistor TR3 may be gradually turned off.
[0062]
In the above example, the capacitor C1 and the discharging resistor R5 are connected between the emitter and the base of the auxiliary transistor TR3 so that the transistor TR3 is gradually turned off by discharging the capacitor C1, but the transistor TR3 is gradually turned off. The means for turning off the power supply is not limited to the above example.
[0063]
In the example shown in FIG. 2, the timing at which the contacts of the spark plug are worn out is determined from the integrated value Ts of the engine operating time. You may make it.
[0064]
FIG. 7 shows another example of the configuration of the ignition device according to the present invention. In this example, the output voltage Vcc of the power supply circuit 5 is applied to ports P3 and P4 of the CPU through resistors R11 and R12, respectively. And switches SW1 and SW2 are connected between P4 and P4 and ground, respectively.
[0065]
In this example, a switching command is given to the CPU 6 by turning on and off the switches SW1 and SW2, thereby switching the set value Td1 of the discharge continuation time, the integrated value of the engine operating time or the integrated value of the number of ignitions (stored in the EEPROM). Reset) can be performed. With this configuration, depending on the state of the air-fuel mixture supplied to the internal combustion engine, the set value Td1 of the discharge duration is switched or the spark plug is replaced when the spark plug is replaced, depending on the combination of the states of the switches SW1 and SW2. Or the integrated value for determining the life of the battery can be reset.
[0066]
In general, when the air-fuel mixture is rich, sufficient ignition performance can be obtained even when the discharge duration is shortened. However, when the air-fuel mixture is lean (lean), the discharge duration is lengthened. It is desirable.
[0067]
In the above description, the configuration of the ignition method and the ignition device is shown for a single cylinder. However, it goes without saying that the present invention can be applied to the ignition method and the ignition device for a multi-cylinder internal combustion engine.
[0068]
【The invention's effect】
As described above, according to the present invention, after the primary current of the ignition coil is cut off, the primary current control switch is turned on when the set discharge time has elapsed, and the current is supplied from the DC power supply to the primary coil of the ignition coil. The discharge generated in the ignition plug is stopped by flowing the electric current, so that the discharge duration can be limited to prevent the discharge duration from becoming unnecessarily long. Therefore, it is possible to prevent the discharge gap of the spark plug from being exhausted early and to reduce the ignition performance, and to maintain the high ignition performance for a long time to stably perform the continuous operation of the engine. There are advantages.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a configuration example of an ignition device according to the present invention.
FIG. 2 is a flowchart showing an algorithm of an interrupt routine executed by a CPU in the ignition device of FIG. 1;
FIG. 3 is a flowchart showing another interrupt routine executed by the CPU in the ignition device of FIG. 1;
FIG. 4 is a flowchart showing yet another interrupt routine executed by the CPU in the ignition device of FIG. 1;
FIG. 5 is a waveform diagram showing voltage and current waveforms of respective parts of the ignition device of FIG. 1;
FIG. 6 is an enlarged waveform diagram schematically showing waveforms of an ignition coil primary current, a secondary voltage, and a secondary discharge current of the ignition device of FIG. 1;
FIG. 7 is a configuration diagram showing another configuration example of the ignition device according to the present invention.
FIG. 8 is a configuration diagram showing a configuration of a conventional ignition device.
FIG. 9 is a waveform diagram showing voltage and current waveforms of respective parts in FIG.
10 is an enlarged waveform diagram schematically showing waveforms of an ignition coil primary current, a secondary voltage, and a secondary discharge current of the ignition device of FIG. 9;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Ignition coil, 2 ... Switch for primary current control, 3 ... Battery (DC power supply), 4 ... Key switch, 6 ... CPU, 7 ... Switch for cutoff control, 8 ... Signal generator, TR1 ... Main transistor, TR3 ... Auxiliary transistor.

Claims (1)

A DC voltage is applied to both ends of a series circuit of an ignition coil, a main transistor having a collector-emitter circuit connected in series to a primary coil of the ignition coil, and a series circuit of the primary coil and a collector-emitter circuit of the main transistor. An internal combustion engine comprising: a DC power supply; and an ignition control unit configured to control the main transistor to be in a conductive state at an energization start position advanced from an ignition position of the internal combustion engine and to set the main transistor to a cutoff state at the ignition position. In the engine ignition device,
  The ignition control unit includes:
  An auxiliary transistor provided to allow a base current to flow from the DC power supply to the main transistor when in a conductive state;
  A cutoff control switch provided so as to bypass the main transistor by cutting off the main transistor by bypassing the base current of the main transistor from the main transistor when in a conductive state;
  Integrating means for integrating the operating time or the number of ignitions of the internal combustion engine,
  Auxiliary transistor driving means for turning on the auxiliary transistor when an energization start position determined at a position advanced from the ignition position of the internal combustion engine is detected,
  Ignition-time cut-off control switch driving means for supplying a drive signal to the cut-off control switch when the ignition position of the internal combustion engine is detected, thereby turning on the cut-off control switch;
  When the integrated value obtained from the integrating means is equal to or less than a set value, a discharge time measuring means for starting measurement of a discharge time set at an ignition position of the internal combustion engine,
  When the integrated value obtained from the integrating means is equal to or less than a set value, when the discharge time measuring means completes the measurement of the set discharge time, the cutoff control switch is turned off, and the integrated value is set. When the discharge time is exceeded, the discharge time cut-off control switch control means for turning off the cut-off control switch at a position delayed from the position at which the discharge time measurement means completes the set discharge time measurement, A position where the base current applied to the auxiliary transistor is gradually reduced from a position further delayed than a position where the discharge time measurement timer completes the measurement of the set discharge time, and a position sufficiently advanced from the energization start position. An auxiliary transistor cutoff control means for controlling the auxiliary transistor to be in a cutoff state,
  An ignition device for an internal combustion engine, comprising:

Images