JP2004084555A - Ignition device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ignition device of an internal combustion engine, capable of preventing a control circuit from malfunctioning due to ignition noise, switching noise and the like, without inserting a filter circuit in the input line of the control circuit. <P>SOLUTION: This ignition device is provided with a pulse signal generating means to repeatedly generate a switching pulse signal after the enumerated value of a counter to count the number of lapses of a prescribed time exceeds a first prescribed value, a switching power supply to output a dc voltage by a switching element switched on and off in response to the switching pulse signal, a trigger signal generating means to return the enumerated value to an initial value when the enumerated value of the counter exceeds a second prescribed value which is larger than the first prescribed value right after the reference position signal of the internal combustion engine is generated, and to generate an ignition trigger signal to indicate ignition timing in the operation cycle of the internal combustion engine, and a boosting circuit to generate a pulse-shaped voltage signal using a dc voltage as a power supply in response to the ignition trigger signal and to apply it to an ignition coil. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ignition device that generates a high voltage to be supplied to a spark plug of an internal combustion engine.
[0002]
[Prior art]
Some ignition devices for internal combustion engines include an ignition timing setting circuit, a switching power supply, and a booster circuit. The ignition timing setting circuit sets an ignition timing of the internal combustion engine and generates an ignition trigger signal at the ignition timing. The switching power supply boosts the battery voltage to generate a DC voltage. The booster circuit is, for example, a CDI (Capacitor Discharge Ignition) type booster circuit, generates a pulsed voltage signal at a timing corresponding to an ignition trigger signal using a DC voltage as a power supply, and supplies the pulsed voltage signal to an ignition coil. To generate a high voltage to be applied.
[0003]
In a conventional ignition device, the above-described ignition timing setting circuit, switching power supply, and booster circuit are usually formed integrally with a control circuit such as a microcomputer. The control circuit also generates a switching pulse signal so that the DC voltage of the switching power supply becomes a predetermined voltage.
[0004]
[Problems to be solved by the invention]
In such a conventional igniter, noise such as ignition noise generated by a large current flowing through the primary winding of an ignition coil and switching noise generated from a switching power supply is mixed into an input line of a control circuit. However, there is a problem that the device may malfunction.
[0005]
To cope with this, an ignition device in which a noise component is reduced by inserting a filter circuit into an input line is already known (for example, Japanese Patent Publication No. Hei 7-56251).
However, the control circuit has a plurality of input lines for various sensors for detecting operating parameters of the internal combustion engine, such as a cam angle sensor and a crank angle sensor, and it is necessary to insert a filter circuit for each input line. Therefore, another problem that the cost is increased has arisen.
[0006]
Therefore, an object of the present invention is to provide an ignition device for an internal combustion engine that can prevent malfunction of a control circuit due to noise such as ignition noise and switching noise without inserting a filter circuit into an input line of the control circuit. is there.
[0007]
[Means for Solving the Problems]
The ignition device according to the present invention includes a detecting means for generating a reference position signal indicating a reference angular position of an operation cycle of the internal combustion engine, a counter for counting the number of elapses of a predetermined time, and a counter value exceeding a first predetermined value. First determining means for determining whether the count value of the counter has exceeded a first predetermined value, a pulse signal generating means for repeatedly generating a switching pulse signal after the first determining means has determined that the count value has exceeded a first predetermined value, and a switching pulse signal. A switching power supply that outputs a DC voltage by a switching element that is turned on and off in response to a second reference value that determines whether a count value of a counter has exceeded a second predetermined value larger than a first predetermined value in response to a reference position signal. When the count value of the counter exceeds the second predetermined value, the count value of the counter is returned to the initial value. An ignition trigger signal generating means for generating an ignition trigger signal indicating an ignition timing in an operation cycle; a booster circuit for generating a pulsed voltage signal using a DC voltage as a power source in response to the ignition trigger signal and applying the generated signal to an ignition coil; , Is provided.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an electric system of an ignition device for an internal combustion engine according to the present invention. As shown in FIG. 1, the ignition device includes a control circuit 1, a DC-DC converter 2, a CDI boosting circuit 3, and an ignition coil 4. The control circuit 1 includes, for example, a microcomputer, and generates an ignition trigger signal and a switching pulse signal by an operation described later. The control circuit 1 is connected to a cam angle sensor 11, a crank angle sensor 12, a throttle sensor 13, an intake pressure sensor 14, and a water temperature sensor 15. The cam angle sensor 11 generates a TDC signal indicating a vicinity of a compression top dead center of a piston as a reference angular position of an operation cycle of the internal combustion engine in association with rotation of a cam shaft (not shown) of the internal combustion engine. The crank angle sensor 12 generates a crank pulse every time the crankshaft rotates by a predetermined angle (for example, 15 degrees) in conjunction with the rotation of the crankshaft (not shown) of the internal combustion engine. The throttle sensor 13 detects the opening of the throttle valve of the internal combustion engine. The intake pressure sensor 14 detects a negative pressure in the intake pipe 1. The water temperature sensor 15 detects an engine cooling water temperature. The throttle sensor 13, the intake pressure sensor 14, and the water temperature sensor 15 output detected values to the control circuit 1 as voltage signals.
[0009]
The DC-DC converter 2 is a switching power supply, and includes a transistor 21, a blocking transformer 22, a diode 23, and resistors 24 and 25. The transistor 21 is an NPN transistor, and its base is connected to the control circuit 1. The emitter of the transistor 21 is connected to ground, and the collector is connected to the blocking transformer 22.
[0010]
The blocking transformer 22 has a primary winding 22a and a secondary winding 22b. One end of the primary winding 22a is connected to the positive output line of the battery voltage VB, and the other end is connected to the collector of the transistor 21. Therefore, when the transistor 21 is on, the battery voltage VB is applied to the primary winding 22a. Since the transistor 21 is repeatedly turned on and off under the control of the control circuit 1, the battery voltage VB is intermittently applied to the primary winding 22a. As a result, a pulsed AC voltage is generated in the secondary winding 22b. The diode 23 is connected to one end of the secondary winding 22b, and the other end is grounded.
[0011]
The diode 23 is for rectification. Resistors 24 and 25 are connected in series between the rectified output line of the diode 23 and the ground. The resistors 24 and 25 constitute a voltage dividing circuit, and divide the DC voltage rectified by the diode 23 and supply the divided voltage to the control circuit 1.
The booster circuit 3 includes a transistor 31, an SCR 32, and a capacitor 33, and performs an operation of generating a high voltage on the secondary winding 4a of the ignition coil 4. The transistor 31 is a PNP transistor whose base is connected to the control circuit 1, whose emitter is grounded, and whose collector is connected to the gate of the SCR 32. An ignition trigger signal is supplied from the control circuit 1 to the base of the transistor 31, and the transistor 31 is turned on according to the ignition trigger signal. The anode of the SCR 32 is connected to the rectified output line of the diode 23 together with one end of the capacitor 33, and the cathode is grounded. When the transistor 31 is turned on, the voltage VB is applied to the gate, and the SCR 32 is turned on.
[0012]
One end of the secondary winding 4b of the ignition coil 4 is connected to the ignition plug 5, and the other end is grounded. Immediately after the SCR 32 changes from off to on, the capacitor 33 is discharged, and the electric charge stored therein causes the voltage across the primary winding 4a of the ignition coil 4 to rise, which causes the secondary winding 4b to ignite. It appears as a high voltage that causes sparks in the plug 5.
[0013]
In the ignition device according to the present invention having such a configuration, the control circuit 1 executes an ignition trigger signal generation process for generating an ignition trigger signal and a switching pulse signal generation process for generating a switching pulse signal. The ignition trigger signal generation process is performed as an interrupt process in accordance with a TDC signal indicating a cylinder compression top dead center generated from the cam angle sensor 11. The switching pulse signal generation processing is repeatedly executed at every predetermined time (for example, 1 msec).
[0014]
As shown in FIG. 2, in the switching pulse signal generation processing, the control circuit 1 first determines whether or not the count value of the counter is smaller than FF (step S1). The counter is formed by software by executing the next step S2, but may be provided as hardware. The counter is out of the counting range when the count value is FF or more. When the count value of the counter <FF, the control circuit 1 increases the count value of the counter by 1 (step S2). It is determined whether the count value of the counter after the increase is 2 or more (step S3). When the count value of the counter <2, the switching pulse signal generation processing is temporarily terminated. On the other hand, if the count value of the counter ≧ 2, a switching pulse signal is generated (step S4), and then the switching pulse signal generation processing is temporarily terminated. In step S4, the pulse width of the switching pulse signal, that is, the duty ratio, is set by calculation or by using a data table according to the output voltage of the voltage dividing circuit by the resistors 24 and 25. The pulse width of the switching pulse signal is set such that the output voltage of the voltage divider becomes a predetermined voltage.
[0015]
The switching pulse signal generated in step S4 turns on / off the transistor 21. As a result, the intermittent voltage VB is applied to the primary winding 22a of the blocking transformer 22, and an AC signal is generated in the secondary winding 22b. The AC signal is half-wave rectified by the diode 23, and the rectified DC voltage is applied to the voltage dividing circuit by the resistors 24 and 25. Therefore, the rectified voltage output from the diode 23 is feedback-controlled to a predetermined voltage by controlling the pulse width of the switching pulse signal. The DC voltage after rectification by the diode 23 charges the capacitor 33.
[0016]
The control circuit 1 executes an ignition trigger signal generation process as an interrupt process when the TDC signal is supplied from the cam angle sensor 11 as described above. In the ignition trigger signal generation processing, as shown in FIG. 3, first, it is determined whether or not the count value of the counter is 5 or more (step S11). When the count value of the counter is 5 or more, the ignition timing is calculated according to each output signal of the crank angle sensor 12, the throttle sensor 13, the intake pressure sensor 14, and the water temperature sensor 15 (Step S12). Thereafter, the count value of the counter is cleared to 0 (step S13), and the generation of the switching pulse signal is stopped (step S14). Further, an ignition trigger signal is output at the ignition timing (step S15). On the other hand, if the count value of the counter is smaller than 5, the interrupt processing is immediately terminated.
[0017]
When the ignition trigger signal is generated by executing step S14, the transistor 31 of the ignition trigger signal is turned on. When the transistor 31 is turned on, the voltage VB is applied to the gate of the SCR 32 via the emitter / collector of the transistor 31 and the SCR 32 is turned on. When the SCR 32 changes from off to on, the capacitor 33 is discharged, and the stored electric charge causes a current to flow through the primary winding 4a of the ignition coil 4, thereby increasing the voltage between both ends of the primary winding 4a. Thereby, a high voltage ignition signal is generated in the secondary winding 4 b and applied to the ignition plug 5.
[0018]
FIGS. 4A to 4G illustrate the relationship between the TDC signal, the ignition trigger signal generation processing, the ignition trigger signal, the ignition signal, the switching pulse signal generation processing, the switching pulse signal, and the count value of the counter.
The switching pulse signal generation processing is periodically executed at intervals of 1 msec, as shown in FIG. Immediately after the count value of the counter reaches 7 in the switching pulse signal generation processing, a TDC signal having a waveform as shown in FIG. The ignition trigger signal generation processing is executed as shown in FIG. 4B in response to the TDC signal, and the count value of the counter is cleared to 0 as shown in FIG. 4G by step S13 in the ignition trigger signal generation processing. Then, the generation of the switching pulse signal is stopped at the timing shown in FIG. In addition, an ignition trigger signal is generated at the timing shown in FIG. 4C in step S15 of the ignition trigger signal generation processing. An ignition signal is generated with a waveform as shown in FIG. 4D based on the ignition trigger signal. The count value of the counter is incremented by one for each subsequent switching pulse signal generation process. Step S4 of the switching pulse signal generation processing is not performed until the count value of the counter becomes 2, and thus the switching pulse signal is not generated in the period t1 when the count value of the counter is 0 or 1. Therefore, since the operation of the DC-DC converter 2 is stopped during this period t1, erroneous ignition of the SCR 32 due to switching noise from the DC-DC converter 2 can be prevented. Further, since the steps S12 to S15 of the ignition trigger signal generation processing are not executed during the period t2 until the count value of the counter reaches 5, even if the ignition trigger signal generation processing is erroneously executed due to noise, the counter is cleared. The switching pulse signal is not stopped and the ignition trigger signal is not generated.
[0019]
【The invention's effect】
As described above, according to the present invention, it is possible to prevent malfunction of the control circuit due to noise such as ignition noise and switching noise without inserting a filter circuit into the input line of the control circuit.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an ignition device to which the present invention is applied.
FIG. 2 is a flowchart showing a switching pulse signal generation process by a control circuit in the apparatus of FIG.
FIG. 3 is a flowchart showing an ignition trigger signal generation process by a control circuit in the apparatus of FIG. 1;
FIG. 4 is a diagram showing operation timings and signal waveforms of each unit of the device of FIG.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 control circuit 2 DC-DC converter 3 step-up circuit 4 ignition coil 22 blocking transformer 32 SCR

Claims (5)

Detecting means for generating a reference position signal indicating a reference angular position of an operation cycle of the internal combustion engine;
A counter for counting the number of elapses of the predetermined time;
First determining means for determining whether or not the count value of the counter has exceeded a first predetermined value;
Pulse signal generating means for repeatedly generating a switching pulse signal after the first determining means determines that the count value of the counter has exceeded a first predetermined value;
A switching power supply that outputs a DC voltage by a switching element that turns on and off according to the switching pulse signal;
Second determining means for determining whether a count value of the counter has exceeded a second predetermined value larger than the first predetermined value in response to the reference position signal;
An ignition trigger for returning the count value of the counter to an initial value when the count value of the counter exceeds the second predetermined value by the second determination means, and generating an ignition trigger signal indicating an ignition timing in the operation cycle; Signal generation means;
An ignition device, comprising: a booster circuit that generates a pulsed voltage signal using the DC voltage as a power supply in response to the ignition trigger signal and applies the generated voltage signal to an ignition coil. 2. The ignition device according to claim 1, wherein the reference position signal is a TDC signal indicating a compression top dead center of the cylinder. 2. The ignition device according to claim 1, wherein the pulse signal generating means sets a duty ratio so that the DC voltage becomes equal to a predetermined voltage, and generates the switching pulse signal having the duty ratio. The ignition device according to claim 1, wherein the pulse voltage signal applied by the booster circuit is boosted by an ignition coil and supplied to a spark plug. 2. The ignition device according to claim 1, wherein the counter, the first determination unit, the pulse signal generation unit, the second determination unit, and the ignition trigger signal generation unit are configured by a control circuit including a microcomputer. .

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