JP4311189B2 - Ignition system for capacitor discharge internal combustion engine - Google Patents

Description

  The present invention relates to a capacitor discharge type ignition device for an internal combustion engine in which an electric charge accumulated in an ignition capacitor is discharged through a primary coil of an ignition coil to induce an ignition operation by inducing a high voltage in a secondary coil of the ignition coil. It is about.

  In a capacitor discharge type internal combustion engine ignition device (hereinafter also referred to as CDI), it is necessary to charge an ignition capacitor provided on the primary side of the ignition coil with a voltage of 2 to several tens of volts. As a power source for charging the ignition capacitor, an exciter coil provided in a magnet generator driven by an internal combustion engine is often used, but an exciter coil that induces a voltage of 2 hundred and several tens of volts has a large number of turns. If the exciter coil is provided in the generator, it is inevitable that the generator becomes large.

  Therefore, as shown in Patent Document 1, a DC converter type capacitor discharge ignition device has been developed in which the ignition capacitor is charged with a voltage obtained by boosting the voltage of the battery with a DC converter (DC booster). However, since this type of ignition device requires a battery, it cannot be applied to an internal combustion engine that drives a vehicle or the like not equipped with a battery.

  In order to solve the above problem, as shown in Patent Document 2, the output of an AC generator coil provided in an AC generator driven by an internal combustion engine is rectified to generate a DC voltage limited to a certain value or less. A rectifying power supply circuit with a voltage adjusting function for output and a power supply capacitor charged with the output voltage of the rectifying power supply circuit are provided, and the voltage at both ends of the power supply capacitor is boosted by a DC converter to charge the ignition capacitor. An AC / DC converter type CDI has been proposed in which a voltage for obtaining the required voltage is obtained.

The AC / DC converter type CDI includes a power generation coil provided in an AC generator driven by an internal combustion engine, and a voltage adjustment function for rectifying the output of the power generation coil and outputting a DC voltage adjusted to a predetermined value or less. Rectified power supply circuit, a power supply capacitor charged with the output voltage of the rectified power supply circuit, a DC converter that boosts the voltage across the power supply capacitor, and an output voltage of the DC converter provided on the primary side of the ignition coil An ignition capacitor that is charged to one polarity at the same time, a discharge thyristor that is conductive to discharge the charge of the ignition capacitor to the primary coil of the ignition coil when an ignition signal is applied, and a rectifying power source A constant voltage power supply circuit that outputs a DC voltage that is limited to a set value or less using the output voltage of the circuit as input, and a power supply that exceeds the specified value from the constant voltage power supply circuit Constituted by a microcomputer for controlling the timing of giving an ignition signal to the discharge thyristor is in the operating state when the given.
JP-A-8-74715 Japanese Patent Laid-Open No. 11-141445

  According to the AC / DC converter type CDI, since it is not necessary to use a battery, weight reduction and cost reduction can be achieved. However, in this method, since the output of the rectifying power supply circuit is lowered when the DC converter operates when the rotational speed of the internal combustion engine is low and the output of the generator is low, a constant voltage power supply that supplies a power supply voltage to the microcomputer The voltage input to the circuit may be insufficient, and the output voltage of the constant voltage power supply circuit may be lower than a specified value (a value necessary for operating the microcomputer).

  When the power supply voltage of the microcomputer becomes lower than the specified value, the microcomputer is reset, and an ignition signal cannot be given to the discharge thyristor, so that the ignition operation cannot be performed. Therefore, when the AC / DC converter type CDI is used, there is a problem that the rotational speed (starting rotational speed) at which the ignition operation is started at the start of the engine becomes high and the startability of the engine is deteriorated.

  An object of the present invention is to prevent the power supply voltage of the microcomputer from decreasing when the engine speed is low, to reduce the engine start speed and improve the engine startability. An object of the present invention is to provide a converter-type capacitor discharge internal combustion engine ignition device.

  The present invention relates to a power generation coil provided in an AC generator driven by an internal combustion engine, and a rectification power supply circuit with a voltage adjustment function that rectifies the output of the power generation coil and outputs a DC voltage adjusted to a predetermined value or less. A power supply capacitor charged with the output voltage of the rectifier power supply circuit, a DC converter that boosts the voltage across the power supply capacitor, and one polarity of the output voltage of the DC converter provided on the primary side of the ignition coil An ignition capacitor to be charged, a discharge thyristor provided to conduct when an ignition signal is applied and discharge the charge of the ignition capacitor to a primary coil of the ignition coil, and an output of the rectifying power supply circuit A constant voltage power supply circuit that outputs a DC voltage that is adjusted to a setting value or less with the voltage input, and a power supply voltage that exceeds the specified value is applied from the constant voltage power supply circuit Target igniter capacitor discharge type internal combustion engine having a microcomputer for controlling the timing of giving an ignition signal to the discharge thyristor becomes operating state can.

  In the present invention, in order to achieve the above-mentioned object, voltage determination means for determining whether or not the output voltage of the rectification power supply circuit exceeds a reference value set higher than the above specified value, and rectification by the voltage determination means When it is determined that the output voltage of the power supply circuit exceeds the reference value, the boost operation of the DC converter is permitted, and when it is determined that the output voltage of the rectified power supply circuit is lower than the reference value, the boost operation of the DC converter is performed. The microcomputer is programmed to constitute the prohibited DC converter control means.

  The reference value of the output voltage of the rectified power supply circuit is set sufficiently higher than the specified value of the power supply voltage of the microcomputer, and the value of the output voltage of the rectified power supply circuit when the DC converter is performing the boosting operation is If the voltage is higher than the reference value, the output voltage of the rectifying power supply circuit when the DC converter performs the boosting operation is the voltage that needs to be input to the constant voltage power supply circuit in order to give the microcomputer a power supply voltage exceeding the specified value. Make sure not to be lower than the minimum value.

  If comprised as mentioned above, the rotational speed which can make a DC converter perform a pressure | voltage rise operation and perform ignition operation without producing the state which a microcomputer resets can be made lower than before. Accordingly, the engine speed can be improved by lowering the rotational speed at which the ignition operation is started when the engine is started than in the prior art.

  In the above configuration, the step-up operation of the DC converter is permitted when the output voltage of the rectifying power supply circuit exceeds the reference value. However, when the output voltage of the generator coil exceeds the reference value, the DC converter The step-up operation may be permitted.

  That is, the microcomputer includes a power generation output determination unit that determines whether or not the output voltage of the power generation coil exceeds a set reference value that is higher than a specified value, and the power generation output determination unit instantaneously determines the output voltage of the power generation coil. When it is determined that the value exceeds the reference value, the step-up operation of the DC converter is permitted, and when the instantaneous value of the output voltage of the power generation coil is determined to be less than the reference value by the power generation output determination means, the DC converter It may be programmed to constitute DC converter control means for prohibiting the boosting operation.

  Also in this case, the reference value of the output voltage of the power generation coil is set sufficiently higher than the specified value of the power supply voltage of the microcomputer, and the value of the output voltage of the power generation coil when the DC converter is performing the boosting operation is If the voltage is higher than the reference value, the output voltage of the rectifying power supply circuit when the DC converter performs the boosting operation is the voltage that needs to be input to the constant voltage power supply circuit in order to give the microcomputer a power supply voltage exceeding the specified value. Make sure not to be lower than the minimum value.

  As described above, according to the present invention, the rotational speed at which the DC converter can perform a boosting operation and perform an ignition operation without causing a state in which the microcomputer is reset can be made lower than before. Therefore, it is possible to improve the startability of the engine by lowering the rotational speed at which the ignition operation is started when the engine is started.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows the configuration of an embodiment of the present invention. In this embodiment, the engine to which the ignition device is applied is a single cylinder internal combustion engine for the sake of simplicity. In FIG. 1, 1 is a power generation coil provided in a magnet type AC generator driven by an internal combustion engine, and 2 has a voltage adjustment function for rectifying the output of the power generation coil and outputting a DC voltage limited to a certain value or less. The rectified power supply circuit 3 includes a power supply capacitor 3 charged with the output voltage of the rectified power supply circuit 2, and a DC converter 4 boosts the voltage across the power supply capacitor.

  5 is an ignition coil, 6 is an ignition capacitor provided on the primary side of the ignition coil and charged to one polarity by the output voltage of the DC converter 4, and 7 is turned on and ignited when an ignition signal Vi is given. A discharge thyristor 8 provided to discharge the charge accumulated in the capacitor 6 to the primary coil of the ignition coil 5; a constant voltage power supply circuit for outputting a constant DC voltage with the voltage across the power supply capacitor 3 as an input; Is a microcomputer that operates when a power supply voltage is applied from the regulator IC 8 and controls the timing (ignition timing) of applying an ignition signal to the discharge thyristor 7.

  More specifically, the rectifying power supply circuit 2 includes a rectifying circuit that rectifies the output of the power generating coil 1 and a voltage adjustment circuit that controls the output voltage of the rectifying circuit to be limited to a predetermined value or less. As the voltage adjustment circuit, for example, a short circuit that short-circuits the power generation coil 1 when the output voltage of the rectifier circuit exceeds a certain value can be used. The output voltage of the rectified power supply circuit 2 is applied to the power supply capacitor 3 through the diode 10.

  The DC converter 4 includes a step-up transformer 401 to which the voltage across the power supply capacitor 3 is applied to the primary coil, a step-up switch 402 connected in series to the primary coil W 1 of the step-up transformer 401, and a step-up transformer 401. The current (secondary current) flowing through the secondary coil W2 is detected, and when the secondary current of the step-up transformer 401 is less than the set value, the step-up switch 402 is turned on, and the secondary current of the step-up transformer becomes greater than or equal to the set value. And a DC converter control circuit 403 that controls on / off of the boost switch 402 in accordance with the secondary current of the boost transformer so that the boost switch 402 is turned off.

  In the illustrated example, a forward diode 404 is connected to the secondary current of the transformer 401 between one end of the secondary coil W 2 of the transformer 401 and the ground, and the voltage at both ends of the diode 404 is converted to the converter control circuit 403. Has been entered. The converter control circuit 403 detects the secondary current of the step-up transformer 401 by detecting the forward voltage drop that occurs across the diode 404 when the secondary current flows through the step-up transformer, and the detected secondary current is When it is less than the set value (including 0 [A]), the boost switch 402 is turned on, and when the detected secondary current reaches the set value, the boost switch 402 is turned off and the secondary of the boost transformer 401 A high voltage of 2 to several tens of volts is induced in the coil. The converter control circuit 403 turns on and off the boost switch 402 only when a boost command is given from the microcomputer 9 to the control terminal 403a, and causes the DC converter 4 to perform a boost operation. When the boost command is not given, the boost switch 402 is kept off to stop the boost operation of the DC converter 4.

  The ignition coil 5 has a primary coil 5a and a secondary coil 5b that are grounded at one end, and one end of an ignition capacitor 6 is connected to a non-ground side terminal of the primary coil 5a of the ignition coil. The other end of the ignition capacitor 6 is connected to the other end of the secondary coil W2 of the step-up transformer 401 through a diode 11 with the cathode facing the ignition capacitor side. The voltage output from the DC converter 4 causes the diode 11 and the ignition coil to be connected. The ignition capacitor 6 is charged to the illustrated polarity through the primary coil 5a.

  A discharge thyristor 7 with the cathode facing the ground side is connected between the other end of the ignition capacitor 6 and the ground, and when an ignition signal (trigger signal) Vi is applied to the gate of the discharge thyristor 7, the thyristor 7 In the on state, the electric charge accumulated in the ignition capacitor 6 is discharged through the primary coil 5a of the ignition coil. Further, the non-grounded side terminal of the secondary coil of the ignition coil 5 is connected through a high-voltage cord to the non-grounded side terminal of the spark plug 12 attached to the cylinder of the internal combustion engine.

  When the ignition signal Vi is applied to the discharge thyristor 7 and the thyristor 7 becomes conductive, the charge accumulated in the ignition capacitor 6 is discharged through the discharge thyristor 7 and the primary coil 5a of the ignition coil 5. A large magnetic flux change occurs in the iron core of the ignition coil 5, and a high voltage is induced in the secondary coil 5b. Since this high voltage is applied to the spark plug 12, a spark discharge is generated in the spark plug and the engine is ignited.

  A microcomputer 9 is provided for controlling the ignition timing of the DC converter 4 and the internal combustion engine. The microcomputer 9 is supplied with power from a regulator IC (constant voltage power circuit) 8 that outputs the DC voltage Vcc adjusted to a set value (for example, 5 [V]) or less by using the DC voltage Vdc output from the rectifier power circuit 2 as an input. The voltage is given. When the power supply voltage Vcc supplied from the regulator IC 8 is within an allowable range of a specified value Vres or more and a rated value (for example, 5 [V]) or less, the microcomputer 9 enters an operating state and is supplied from the regulator IC 8. When the power supply voltage Vcc falls below the specified value Vres, it is reset to stop its operation.

  Pulse signals Vs1 and Vs2 output from a signal generator 13 attached to the internal combustion engine are input to ports B1 and B2 of the microcomputer 9 through waveform shaping circuits 14 and 15, respectively. For example, the signal generator 13 detects edges on the front end side and the rear end side in the rotational direction of a reluctator (an arc-shaped protrusion or recess extending in the circumferential direction of the rotor) provided on a rotor attached to the crankshaft. It consists of a known one that generates pulse signals Vs1 and Vs2. The crank angle position at which the signal generator 13 generates the pulse signal Vs1 is set, for example, to a position further advanced than the maximum advance position of the engine ignition position (crank angle position corresponding to the ignition timing). The generated crank angle position is set to a position suitable as an ignition position at the start of the engine and at an extremely low speed. The position where the pulse signal Vs1 is generated is used as a reference position when detecting the calculated ignition timing of the engine.

  Further, in order to control the DC converter 4, a DC voltage Vdc obtained from the rectified power supply circuit 2 is inputted to the A / D input terminal A 1 of the microcomputer 9 through a detection circuit (not shown). The microcomputer 9 reads a digital conversion value of the DC voltage Vdc at a predetermined sampling period, and controls the DC converter according to the read voltage value. The microcomputer also controls the timing (ignition timing) for giving the ignition signal to the discharge thyristor 7 based on the engine rotation information (crank angle information and rotation speed information) obtained from the pulse signal given from the signal generator 13. .

  A voltage for detecting the voltage Vc at both ends of the ignition capacitor 6 in order to perform control to stop the boosting operation of the DC converter 4 when the voltage Vc at both ends reaches the set value Vcs when the ignition capacitor 6 is charged. A detection circuit 16 is provided, and the output of this voltage detection circuit is input to the other A / D input terminal A2 of the microcomputer. The illustrated voltage detection circuit 16 is composed of a voltage dividing circuit constituted by resistors R1 and R2 connected in series with each other, and is connected between output terminals of the DC converter 4.

The microcomputer 9 constitutes at least the following means by executing a program stored in a non-volatile memory such as a ROM or EEPROM in order to control the DC converter and the ignition timing.
(A) Voltage determination means for determining whether the output voltage of the rectified power supply circuit 2 exceeds a reference value set higher than the specified value.
(B) When the voltage determining means determines that the output voltage of the rectified power supply circuit exceeds the reference value, the boost operation of the DC converter 4 is permitted, and it is determined that the output voltage of the rectified power supply circuit is equal to or lower than the reference value. DC converter control means for prohibiting the step-up operation of the DC converter 4 when being done.
(C) In order to prevent the charging voltage of the ignition capacitor 6 from becoming excessive, when the voltage Vc detected by detecting the voltage Vc across the ignition capacitor reaches the set value Vcs, the boost operation of the DC converter is performed. Converter stop means when capacitor charging is stopped.
(D) Ignition converter stop means for stopping the boosting operation of the DC converter 4 when an ignition signal is applied to the discharge thyristor in order to prevent the output of the DC converter 4 from being short-circuited through the discharge thyristor .
(E) Rotational speed detection means for detecting the rotational speed of the internal combustion engine from the generation interval (time required for one rotation of the crankshaft) of the pulse signal given from the signal generator 13 through the waveform shaping circuit 14 or 15.
(F) Ignition position calculation means for calculating the ignition position (crank angle position corresponding to the ignition timing) of the internal combustion engine with respect to the rotation speed detected by the rotation speed detection means.
(G) Ignition timer timing data calculation means for calculating ignition timer timing data to be measured by the ignition timer in order to detect the calculated ignition position.
(H) When the signal generator 13 generates the pulse signal Vs1, the ignition timer timing data calculated by the ignition timer timing data calculating means is set in the ignition timer to start measurement of the timing data. Ignition command generating means for generating an ignition command signal when the measurement of time data is completed.

  The ignition timer timing data is the time that the ignition timer needs to measure until the crankshaft rotates from the reference position where the signal generator 13 generates the pulse signal Vs1 to the calculated ignition position.

  The microcomputer 9 gives a boost command from the port C to the DC converter control circuit 403 when the DC converter control means permits the DC converter boost operation, and the DC converter control means prohibits the DC converter boost operation. The supply of the boost command is stopped.

  The microcomputer 9 also gives an ignition command signal from the port D to the ignition signal output circuit 17 when the ignition timer completes the measurement of the timing data. The ignition signal output circuit 17 gives an ignition signal Vi to the discharge thyristor 7 when an ignition command signal is given from the microcomputer 9 to perform an ignition operation.

  FIG. 2 is a flowchart showing a routine algorithm executed by the microcomputer at a predetermined sampling period in order to configure the voltage determination means and the DC converter control means. In this algorithm, first, in step 1, the A / D conversion value of the output voltage of the rectifying power supply circuit 2 is read, and the A / D conversion value (output voltage of the rectifying power supply circuit) read in step 2 is higher than the reference value. Determine whether it is larger. As a result, when the A / D conversion value is larger than the reference value, the routine proceeds to step 3 and permits the DC converter to perform the boosting operation, and then this routine is terminated. When it is determined in step 2 that the A / D conversion value is equal to or less than the reference value, the routine proceeds to step 4 where the DC converter 4 is prohibited from performing a boosting operation, and then this routine is terminated.

  In the present invention, the value of the output voltage of the rectifying power supply circuit 2 in a state in which the DC converter is performing the boosting operation is set so that the reference value is set sufficiently higher than the specified value of the power supply voltage of the microcomputer. If it is above, the minimum value of the voltage that needs to be input to the regulator IC in order for the output voltage of the rectifying power supply circuit 2 when the DC converter 4 performs the boosting operation to give the power supply voltage exceeding the specified value to the microcomputer. So that it is never lower.

  In the case of the algorithm shown in FIG. 2, voltage judging means for judging whether or not the output voltage of the rectified power supply circuit exceeds the reference value set higher than the specified value is configured in step 2 of FIG. When the output voltage of the rectified power supply circuit is determined by the voltage determining means to exceed the reference value by steps 3 and 4 in the figure, the boost operation of the DC converter is permitted, and the output voltage of the rectified power supply circuit is DC converter control means for prohibiting the boosting operation of the DC converter when it is determined that the value is less than or equal to the value.

  Of the function realizing means realized by the microcomputer, in order to prevent the charging voltage of the ignition capacitor 6 from becoming excessive, the voltage Vc detected by detecting the voltage Vc across the ignition capacitor reaches the set value Vcs. In order to prevent the output of the DC converter 4 from being short-circuited through the discharging thyristor, an ignition signal is given to the discharging thyristor, and the converter stopping means upon completion of capacitor charging for stopping the boosting operation of the DC converter. The ignition converter stop means for stopping the step-up operation of the DC converter 4 during normal operation is normally provided in the CDI for charging the ignition capacitor by the DC converter 4, and is therefore provided in the microcomputer to realize this means. A description of the algorithm of the program to be executed is omitted.

  Similarly, a rotational speed detecting means for detecting the rotational speed of the internal combustion engine from the generation interval of the pulse signal supplied from the signal generator through the waveform shaping circuit, and ignition of the internal combustion engine with respect to the rotational speed detected by the rotational speed detecting means Ignition position calculation means for calculating the position, ignition timer timing data calculation means for calculating the ignition timer timing data to be measured by the ignition timer to detect the calculated ignition position, and a pulse signal Vs1 indicating that the signal generator indicates the reference position The ignition timer timing data calculated by the ignition timer timing data calculation means is set in the ignition timer and measurement of the timing data is started. When the ignition timer completes measurement of the timing data, the ignition command The ignition command generating means for generating a signal is also usually used in CDI in which the ignition timing is controlled by a microcomputer. Since it is intended to be eclipsed, omitting description thereof about the program to be executed by the microcomputer in order to achieve these means.

  The output voltage waveform of the rectifying power supply circuit 2 in the above embodiment is shown by a solid line in FIG. 3A, and the waveform of the voltage Vc across the ignition capacitor and the waveform of the output voltage Vcc of the regulator IC 8 are shown in FIG. Indicated. For comparison, the waveform of the voltage Vc across the ignition capacitor and the output voltage waveform of the regulator IC 8 in the conventional ignition device are shown in FIG. In FIG. 3A, Vref indicates a reference value of the output voltage Vdc of the rectifying power supply circuit.

  3B and 3C, Vres is a specified value (reset level) of the power supply voltage of the microcomputer 9, and the microcomputer is in an operating state when the power supply voltage Vcc exceeds the specified value. Thus, the power supply voltage Vcc is reset to become the specified value Vres or less, and the operation is stopped. Vf in FIG. 3C indicates the output voltage level of the regulator IC when the output voltage of the rectifying power supply circuit becomes equal to the reference value Vref in the present invention.

  In the CDI according to the present invention, the boost operation of the DC converter 4 is permitted only during the period T1 when the output voltage of the rectifying power supply circuit 2 exceeds the reference value Vref by the action of the DC converter control means. The DC converter 4 is prohibited from boosting operation when the output voltage is equal to or lower than the reference value Vref. When the capacitor charging is completed, the converter stopping means stops the boosting operation of the DC converter 4 when the charging voltage Vc of the ignition capacitor 6 reaches the set value Vcs, and the ignition converter stopping means works to discharge. While the ignition signal is supplied to the thyristor 7 for use, the boosting operation of the DC converter 4 is stopped. In FIG. 3C, Tc1 and Tc2 indicate periods during which the ignition capacitor is charged in the AC / DC converter type CDI according to the present invention. In FIG. 3B, Tc represents a period during which the ignition capacitor is charged in the conventional AC / DC converter type CDI.

With reference to FIGS. 3A and 3C, the operation of the CDI according to the present invention when the rotational speed of the engine is relatively low will be described as follows.
In the example shown in FIG. 3, the output voltage Vdc of the rectifying power supply circuit 2 exceeds the reference value Vref at time t1, but at this time, the charging voltage (voltage across the capacitor 6) Vc of the ignition capacitor 6 has already been set. Since the value Vcs is reached, the DC converter 4 stops the boosting operation. When the ignition signal Vi is given from the microcomputer 9 to the discharge thyristor 7 through the ignition signal output circuit 17 at the ignition timing ti1, the thyristor 7 is turned on, so that the charges accumulated in the ignition capacitor 6 are transferred to the thyristor 7 and the ignition coil. The primary coil 5a is discharged and an ignition operation is performed. At this time, the voltage Vc across the ignition capacitor falls to zero, but the DC converter 4 stops the boosting operation while the ignition thyristor 7 is given an ignition signal. When the ignition signal applied to the discharge thyristor 7 disappears at time t2, the boost operation of the DC converter 4 is started and the ignition capacitor 6 is charged. When the output voltage of the rectified power supply circuit becomes equal to or lower than the reference value Vref at time t3, the DC converter 4 stops the boosting operation, and the charging of the ignition capacitor 6 is interrupted. Next, when the output voltage Vdc of the rectified power supply circuit exceeds the reference value Vref at time t4, the DC converter 4 resumes the boosting operation, and the ignition capacitor 6 is charged again. When the charging voltage Vc of the ignition capacitor 6 reaches the set value Vcs at the time t5, the DC converter 4 stops the boosting operation by the action of the converter stop means when the capacitor charging is completed, so that the charging of the ignition capacitor 6 stops. . Thereafter, the voltage Vc across the ignition capacitor is held at the set value Vcs until the next ignition is performed.

  When an ignition signal is given to the discharge thyristor 7 at the next ignition timing ti2, an ignition operation is performed. When the supply of the ignition signal to the discharge thyristor 7 is stopped at time t6, the boosting operation of the DC converter 4 is started, and charging of the ignition capacitor 6 is started. When the output voltage of the rectified power supply circuit 2 becomes equal to or lower than the reference value Vref at time t7, the DC converter 4 stops the boosting operation, and the charging of the ignition capacitor 6 is interrupted. Next, when the output voltage of the rectified power supply circuit 2 exceeds the reference value Vref at time t8, the DC converter boost operation is started, and charging of the ignition capacitor 6 is resumed. When the charging voltage Vc of the ignition capacitor reaches the set value Vcs at time t9, the boost operation of the DC converter is stopped, and charging of the ignition capacitor 6 is stopped. Thereafter, the same operation is performed to ignite the engine.

  As described above, according to the present invention, when the output voltage of the rectifying power supply circuit 2 becomes equal to or lower than the reference value Vref, the boost operation of the DC converter 4 is prohibited so that the converter does not perform the boost operation. Therefore, it is possible to prevent the microcomputer from being reset when the power supply voltage Vcc of the microcomputer output from the regulator IC becomes lower than the specified value Vres when the engine rotates at a low speed, and the ignition operation can be performed without any trouble.

  On the other hand, in the conventional AC / DC converter type CDI, the DC converter 4 is caused to perform the boosting operation even during the period when the output voltage of the rectified power supply circuit 2 is equal to or lower than the reference value Vref. As shown in FIG. 3, the output voltage Vcc of the regulator IC may drop below a specified value Vres when the engine rotates at a low speed, and the microcomputer may be reset. When the microcomputer is reset, the operation is stopped, and an ignition signal cannot be given to the discharge thyristor 7, so that the ignition operation cannot be performed.

  In the CDI according to the present invention, when the engine speed increases, the period during which the output voltage of the rectified power supply circuit 2 is equal to or lower than the reference value Vref is shortened. Shorter.

  In the above embodiment, the output voltage of the rectified power supply circuit 2 is input to the A / D input port A1 of the microcomputer, and the boost operation of the DC converter is prohibited when the output voltage of the rectified power supply circuit 2 is below the reference value Vref. However, when the output voltage of the generator coil 1 is input to the A / D input port A1 of the microcomputer and the output voltage of the generator coil 1 is lower than the reference value Vres set higher than the specified value Vres. In addition, the DC converter control means may be configured to prohibit the step-up operation of the DC converter. In this case, the output voltage of the generator coil 1 is preferably input to the A / D input port A1 of the microcomputer 9 in a form converted into a full-wave rectified waveform through a voltage detection circuit having a full-wave rectifier circuit.

  That is, the microcomputer 9 determines whether or not the output voltage of the power generation coil 1 exceeds a reference value set higher than a specified value, and the output voltage of the power generation coil 1 by the power generation output determination means. When it is determined that the instantaneous value exceeds the reference value, the step-up operation of the DC converter is permitted, and when the instantaneous value of the output voltage of the power generating coil is determined to be less than the reference value by the power generation output determination means It may be programmed to constitute DC converter control means for prohibiting the boosting operation of the DC converter.

  In the above description, the DC converter control circuit 403 detects the secondary current of the step-up transformer 401, turns on the step-up switch 402 when the detected secondary current is less than the set value, and the detected secondary current is The boosting switch 402 is configured to be turned off when the set value is reached. However, an oscillator that oscillates at a constant frequency is provided, and the boosting switch 402 is turned on / off by the output of the oscillator. The present invention can also be applied when using a DC converter.

  In the example shown in FIG. 1, one end of the ignition capacitor 6 is connected to the non-grounded terminal of the primary coil 5a of the ignition coil, but the ignition capacitor 6 is connected between the cathode of the diode 11 and the ground, A configuration in which the discharge thyristor 7 is connected between the non-ground side terminal of the capacitor 6 and the non-ground side terminal of the primary coil 5a (a configuration in which the positions of the ignition capacitor 6 and the discharge thyristor 7 are interchanged in FIG. 1). Of course, the present invention can also be applied when an ignition circuit having the same is used.

  In the example shown in FIG. 1, the internal combustion engine is assumed to be one cylinder, but the present invention can of course be applied to an AC / DC converter type CDI that ignites a multi-cylinder internal combustion engine.

It is the circuit diagram which showed the structure of embodiment of this invention. It is the flowchart which showed an example of the algorithm of the program which makes a microcomputer perform in order to comprise a voltage determination means and a DC converter control means in embodiment of this invention. FIG. 2 is a waveform diagram showing a voltage waveform of each part of the ignition device shown in FIG. 1 and a voltage waveform of each part of a conventional ignition device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Generating coil 2 Rectification power supply circuit with voltage adjustment function 3 Power supply capacitor 4 DC converter 5 Ignition coil 6 Ignition capacitor 7 Discharge thyristor 8 Regulator IC (constant voltage power supply circuit)
9 Microcomputer

Claims (2)

A generator coil provided in an AC generator driven by an internal combustion engine; a rectifier power supply circuit having a voltage adjustment function for rectifying the output of the generator coil to output a DC voltage adjusted to a predetermined value or less; and the rectifier. A power supply capacitor that is charged with the output voltage of the power supply circuit, a DC converter that boosts the voltage across the power supply capacitor, and a primary polarity that is provided on the primary side of the ignition coil and is charged to one polarity with the output voltage of the DC converter An ignition capacitor, a discharge thyristor provided to discharge when the ignition signal is applied and discharge the charge of the ignition capacitor to the primary coil of the ignition coil, and an output voltage of the rectifying power supply circuit A constant voltage power supply circuit that outputs a DC voltage adjusted to a setting value or less as an input, and a power supply voltage exceeding a specified value is applied from the constant voltage power supply circuit. The ignition device for capacitor discharge type internal combustion engine having a microcomputer for controlling the timing of giving an ignition signal to the discharge thyristor is in the operating state when being,
The microcomputer includes: voltage determination means for determining whether or not the output voltage of the rectified power supply circuit exceeds a reference value set higher than the specified value; and the output voltage of the rectified power supply circuit by the voltage determination means. Is permitted to exceed the reference value, and the boost operation of the DC converter is permitted, and when the output voltage of the rectified power supply circuit is determined to be less than the reference value, the boost operation of the DC converter is prohibited. Programmed to constitute DC converter control means;
An ignition device for a capacitor discharge internal combustion engine. A generator coil provided in an AC generator driven by an internal combustion engine; a rectifier power supply circuit having a voltage adjustment function for rectifying the output of the generator coil to output a DC voltage adjusted to a predetermined value or less; and the rectifier. A power supply capacitor that is charged with the output voltage of the power supply circuit, a DC converter that boosts the voltage across the power supply capacitor, and a primary polarity that is provided on the primary side of the ignition coil and is charged to one polarity with the output voltage of the DC converter An ignition capacitor, a discharge thyristor provided to discharge when the ignition signal is applied and discharge the charge of the ignition capacitor to the primary coil of the ignition coil, and an output voltage of the rectifying power supply circuit A constant voltage power supply circuit that outputs a DC voltage adjusted to a setting value or less as an input, and a power supply voltage exceeding a specified value is applied from the constant voltage power supply circuit. The ignition device for capacitor discharge type internal combustion engine having a microcomputer for controlling the timing of giving an ignition signal to the discharge thyristor is in the operating state when being,
The microcomputer includes: a power generation output determination unit that determines whether or not an output voltage of the power generation coil exceeds a reference value that is set higher than the specified value; and the output voltage of the power generation coil by the power generation output determination unit. When it is determined that the instantaneous value exceeds the reference value, the step-up operation of the DC converter is permitted, and the power generation output determining means determines that the instantaneous value of the output voltage of the power generating coil is equal to or less than the reference value. Programmed to constitute DC converter control means for prohibiting the boosting operation of the DC converter,
An ignition device for a capacitor discharge internal combustion engine.

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