JPH0672586B2 - Capacity discharge ignition device for internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ignition device for an internal combustion engine, and more particularly to a capacity discharge type ignition device, in which optimal ignition control is performed according to the load state and the rotation speed of the internal combustion engine. For improvements to do.

[Prior Art] Most of the current ignition devices for internal combustion engines for automobiles obtain a high voltage on the secondary side of the ignition coil by abruptly cutting off the primary current of the ignition coil. It is a so-called current interruption type in which a discharge spark is blown to a spark plug. In fact, this type of ignition device is excellent in that it can generate a discharge spark having a long duration.

However, as has been conventionally said, the capacity discharge ignition device, which can obtain a spark having an extremely fast rise, is more advantageous for the contamination of the spark plug, etc.,
While being put to practical use for two-wheeled vehicles and the like, even for four-wheeled automobiles, research into practical use of this capacitive discharge ignition device is still ongoing from various viewpoints.

In the first place, the capacitive discharge type is a stored charge that has been stored in the energy storage capacitor in advance by turning on the switching element by the ignition signal emitted from the ignition signal processing circuit when the ignition timing detection circuit detects the ignition timing. Is rapidly discharged to the primary winding of the ignition coil to obtain a high voltage in the secondary winding of the ignition coil, and this high voltage causes discharge sparks to the ignition plug. Of course, this is common to all the conventional examples, but not only that, but also the switching element, such as the current control type represented by the thyristor shown in the drawing of Japanese Utility Model Publication No. 61-76125. That is, when a control current flows into the control terminal (gate terminal) to trigger it and a capacitor discharge current flows as the element current, It is also common to use a switching element of a type that is not reset unless the discharge current ends or flows in the opposite direction due to the presence of a resonance system.

[Problems to be Solved by the Invention] In the conventional capacitive discharge ignition device, as described above, since the thyristor or a similar current control type switching element is used as the switching element, energy storage is performed at each ignition. All the accumulated charge of the capacitor was used up.

In other words, once the switching element is triggered, at least the capacitor discharge current, which is the element current of the switching element, almost disappears, or unless the current direction reverses due to resonance, the switching element again
Since it cannot return to the OFF state, regardless of the load state of the internal combustion engine and the difference in rotation speed, a constant amount of charge, which is the maximum amount of charge supplied from the capacitor, is always discharged to the ignition coil primary winding. It was.

Therefore, under certain load conditions and certain rotational speeds,
Even if it is possible to give sufficient ignition energy to the spark plug, the ignition energy will be insufficient under different conditions,
In some cases, there was a misfire, and conversely, if a capacitor is designed with a large capacity so that such a misfire may occur and a large amount of charge is always discharged, the efficiency will deteriorate extremely,
Depending on the load condition and rotation speed at that time, there is a waste of giving excessive ignition energy, or the iron core of the ignition coil may be magnetically saturated.

The present invention solves the above-mentioned conventional drawbacks and provides a capacity discharge ignition device for an internal combustion engine, which can ensure efficient use of energy and reliable ignition.

[Means for Solving the Problems] In order to achieve the above object, the present invention turns on a switching element by an ignition signal emitted from an ignition signal processing circuit based on an ignition timing signal from an ignition timing detection circuit to store energy. As a capacitive discharge ignition device for an internal combustion engine, a high voltage is obtained in the secondary winding of the ignition coil by discharging the accumulated charge of the capacitor to the primary winding of the ignition coil, and a spark is discharged to the spark plug by this high voltage. First, we propose the use of a voltage-controlled insulated gate switching element that can control on / off at high speed by a voltage signal as the switching element.

In other words, as represented by the thyristor used in the past, once the trigger is applied, it cannot be turned off unless the element current is stopped, and the switching speed itself is not high. A field effect transistor (FET) or insulated gate bipolar transistor (IGBT) is used without using an element.

On the other hand, an engine rotation speed detection circuit for detecting the rotation speed of the internal combustion engine and an operating state detection circuit for detecting the load state of the internal combustion engine are provided, and the switching element is selected as described above. The ignition signal processing circuit for generating an ignition signal for turning off the power is made up of a determination unit having the following functions and an ignition signal generation unit.

That is, the determination unit determines whether the internal combustion engine is in a relatively low load state or a high load state based on the detection signal from the operating state detection circuit, and determines the rotation speed detection signal from the engine rotation speed detection circuit. Based on the above, it is determined whether the internal combustion engine is in a relatively low rotation state or a high rotation state.

On the other hand, the ignition signal creation unit, based on the judgment of the judgment unit,
When the internal combustion engine is in a relatively low load state, a single pulse voltage waveform with a relatively narrow pulse width is created as an ignition signal, and the internal combustion engine is in a relatively high load state and a relatively low rotation speed. In the case of the state, a plurality of continuous pulse voltage waveforms, each of which has a relatively narrow pulse width but is repeatedly emitted a predetermined number of times, are created as appropriate ignition signals at that time.

Further, the internal combustion engine is in a relatively high load state, and
When in a relatively high rotation state, the ignition signal creation unit creates a single pulse voltage waveform with a relatively wide pulse width as an appropriate ignition signal at this time.

As is apparent, each of the determination unit and the ignition signal generation unit can be configured by hardware according to the existing circuit configuration technology, and the determination and rotation of the internal combustion engine operating state (load state) can be performed. The number of judgments, and based on the judgment results, when creating an ignition signal into the corresponding pulse voltage waveform at each time, if appropriate software is constructed, those judgments and ignition signal preparations -It can be configured substantially by using a computer.

[Operation] According to the present invention, when the load of the internal combustion engine is relatively light,
In other words, a normal operating state in which it is unlikely that a particularly heavy load is applied (hereinafter, this is called a steady state for convenience)
Below, the ignition signal creation unit creates an ignition signal that is a voltage signal with a relatively narrow pulse width, regardless of the number of revolutions of the internal combustion engine, based on the judgment of the judgment unit in the ignition signal processing circuit. . Therefore, the voltage-controlled insulated gate type switching element by FET or IGBT is also turned on for a short time according to this short pulse width. Further, the rising transition and the falling transition at this time are sufficiently fast in this type of voltage control insulated gate type switching element as compared with the conventional current control type switching element.

Therefore, although there is a convenience at the time of high load and low rotation state described later, if the energy storage capacitor is selected to have a large capacity to some extent, even if it is such a short time width, it can be used as the primary winding of the ignition coil. Has been long known as a major feature of this type of capacitive discharge ignition device because a sufficient amount of electric charge is discharged to the secondary side of the ignition coil for an internal combustion engine in a steady state. The quickness of rising of the discharge waveform and the strength of the spark plug against contamination are further enhanced.

However, turning on the switching element for such a short time means that the capacitance of the energy storage capacitor is selected to be large to some extent as described above.
Such short time charge discharge does not completely discharge all the accumulated charge of the energy storage capacitor, but rather
This means that a state in which a sufficient amount of charge is left can be realized.

Therefore, if the load of the internal combustion engine becomes heavier than it can be considered to be steady, for example, when the driver depresses the accelerator, what is the vehicle speed that can be obtained by stepping on this level? On the other hand, according to the present invention, the residual charge of the energy storage capacitor is effectively used in a situation where the vehicle speed does not increase in spite of stepping on the accelerator, such as when climbing a slope.

That is, when the determination unit determines that the internal combustion engine is in a high load state, first, if the rotation speed of the internal combustion engine is relatively low, the ignition signal generation unit in the ignition signal processing circuit determines that each pulse width is As in the case of the single pulse voltage waveform described above, the ignition signal is generated in such a form that the pulse waveform is continuously generated a plurality of times even if it is narrow.

Therefore, the switching element is repeatedly turned on and off a plurality of times per unit ignition time, and as described above, if the capacity of the energy storage capacitor has a margin, the primary of the ignition coil is changed each time. Since the winding can be supplied with a sufficient amount of discharge charge from the capacitor, a high voltage can be obtained several times continuously on the secondary side of the ignition coil and several times continuously on the spark plug. The ignition sparkle is improved because a discharge spark is generated.

On the other hand, even under the same high load condition, when the number of revolutions of the internal combustion engine is high, the ignition signal generation unit uses a relatively wide pulse width as an ignition signal instead of a plurality of pulse voltage waveforms at low revolutions. Create a single pulse voltage waveform with.

Therefore, since the switching element can maintain the ON state for a relatively long time corresponding to the relatively wide pulse width, the amount of discharge of the charge accumulated in the energy storage capacitor increases correspondingly, and the ignition coil Since the discharge energy itself obtained on the next side also increases, its crest value also increases, and its duration also increases, an optimum discharge spark waveform can be obtained at the time of the high load and high rotation. The reason why multiple sparks are not generated at high speed and one discharge spark with a long duration like this is considered to be that the time from ignition to explosion is short and many consecutive ignitions become useless or impossible. Because it will be done.

[Embodiment] FIG. 1 shows an embodiment of a capacitive discharge ignition device constructed according to the present invention, particularly with respect to its circuit configuration.

To explain, the output voltage of the vehicle-mounted battery 10 is DC-DC.
The voltage is sufficiently boosted by the converter 20, and the energy storage capacitor 30 is charged by the output of the DC-DC converter 20.

Since the step-up ratio of the DC-DC converter 20 is typically required to be about 10 times, it is not limited and is merely for reference. However, the DC-DC converter 20 having the configuration as shown in FIG. 4 is used. Is common.

That is, using the transformer 23, the primary current that can flow from the battery 10 to the primary winding of the transformer 23 is interrupted by the switching element 22, and the boosted AC output generated at both ends of the secondary winding of the transformer 23 is thereby converted to the diode 24. Rectify and output. The switching element 22 is turned on / off by a drive signal generated by the switching signal generation circuit 21 at a predetermined frequency.

In the case of the present invention, the charge stored in the energy storage capacitor 30 as described above is turned on by the switching element 50, which is limited to the voltage control insulated gate switching element.
Each time it is turned on, and for the time it is on, it is discharged to the primary winding 41 of the ignition coil 40, and in response thereto, a high voltage is induced in the secondary winding 42 of the ignition coil, which causes ignition. When applied to the plug P, discharge sparks fly to the discharge gap of the spark plug P.

However, as described above, in the present invention, the switching element 50 that turns on / off the primary current of the ignition coil 40 excludes a current control type such as a thyristor conventionally used, and a voltage control insulated gate type switching element. As one of the cases due to limited use, FIG. 1 shows an example of use of a field effect transistor (FET). This is an insulated gate bipolar transistor (IGBT) as shown in FIG. ) Can also be substituted.

That is, in FIG. 1, the nodes for the drain, gate, and source terminal electrodes of the FET 50 are labeled with N ₁ , N ₂ ,
Although N ₃ is attached, the FET 50 is removed from these nodes N ₁ , N ₂ , N ₃ , and as shown in FIG. 5, those nodes N ₁ , N ₂ ,
The collector, the gate, and the emitter of the IGBT 50 may be connected to N ₃ , respectively, and even if it does so, the contents described below do not require any change in that respect.

The voltage-controlled insulated gate switching element 50 is an ignition signal generated by an ignition signal processing circuit 90 constructed according to the present invention.
Although its on / off is controlled by Vd, particularly in the case of this embodiment, switching is performed when the ignition signal Vd becomes a positive and significant voltage value according to the power supply polarity and the polarity of the switching element 50 used. The element 50 is configured to turn on and turn off when the voltage becomes equal to or lower than a predetermined positive voltage value which is close to the ground potential.

The ignition signal processing circuit 90 includes an operating state detection circuit for the internal combustion engine.
The detection signal from 60, the detection signal from the rotation speed detection circuit 70 of the internal combustion engine, and the ignition timing signal from the ignition timing detection circuit 80, which may have a normal configuration including a crank sensor and the like, are given.

The relationship between each of the detection circuits 60, 70, 80 and the ignition signal processing circuit 90 is well shown in FIG. 2, and in FIG. 3, the relationship of the ignition signal Vd output from the ignition signal processing circuit 90 is shown. Sometimes voltage waveforms are shown.

The ignition signal processing circuit 90 includes the judgment units 91 and 92 and the judgment units 91 and 92.
In accordance with the result of the determination, the generating unit 93, 94, 95 for generating an ignition signal Vd having an appropriate pulse voltage waveform at any given time is included.

As I mentioned a little earlier, such an ignition signal processing circuit
With respect to each of the circuit units 91 to 95 in 90, it is possible to configure them all by hardware, or at least a part of their functions is realized by software by a microcomputer operated by an appropriate program. Therefore, in FIG. 2, it can be seen that each of the circuit portions 91 to 95 is a hardware circuit portion, or the ignition signal processing circuit portion.
It was devised so that it can be seen as each step part in a kind of flow chart showing the overall processing within 90.

The rotation speed detection circuit 70 of the internal combustion engine can be extremely easily constructed by using a known existing suitable rotation speed sensor, and is rather already mounted on a vehicle for a purpose different from the present invention. The detection output of the rotation speed detection circuit 70 is the ignition signal processing circuit 90.
It is given to the number-of-rotations judgment part 91 inside.

Further, the operating state detection circuit 60 of the internal combustion engine detects the load state of the internal combustion engine.
It can be configured by using an existing throttle (accelerator) opening sensor.

For example, in a steady state where the internal combustion engine is not particularly heavily loaded, if a map is prepared for the throttle opening and the internal combustion engine speed, the throttle opening or access from the throttle opening sensor at that time is accessed. When the actual rotation speed of the internal combustion engine at that time is lower than the amount of depression, for example, by means stored in the map, it is determined that the internal combustion engine is under a heavier load than in the steady state. be able to. To put it simply,
As mentioned in the action section above, when the driver steps on the accelerator, if it normally runs a little faster if I step on this amount, such a high load state is as described above. It can be detected electrically.

Hereinafter, the operation of the ignition signal processing circuit 90 having such circuit units 91 to 95 will be described.

The operating state determination unit 92 determines that the current rotational speed of the internal combustion engine with respect to the current throttle opening degree (or accelerator depression amount), for example, does not apply a high load to the internal combustion engine and is in a steady state. When it is determined that there is a correspondence relationship in the case, regardless of the determination result of the rotation speed determination unit 91,
In other words, regardless of whether the internal combustion engine is rotating at a relatively low speed or at a high speed, among the three ignition signal generating units 93, 94, 95 shown in the figure, the ignition signal generating unit Only 93 is valid.

Then, when an ignition timing detection signal is sent from the ignition timing signal detection circuit 80 to the ignition signal generation unit 93, the ignition signal generation unit 93 causes the ignition signal generation unit 93 to output the ignition timing detection signal as indicated by a part (a) in FIG. As the ignition signal Vd, a single pulse voltage waveform having a relatively narrow pulse width is created and output.

As a result, the ignition operation 96 is shown in FIG. 2, but as is apparent from FIG. 1 as well, the switching signal 50 is generated by the ignition signal Vd which is the one-shot narrow pulse voltage waveform. After being turned on for a relatively short time corresponding to the pulse width, it is turned off again with the fall of the pulse voltage waveform.

Therefore, if the capacity of the energy storage capacitor 30 is selected to be a certain size, the energy storage capacitor 30 can be stored in such a low load state per ignition operation regardless of the number of revolutions of the internal combustion engine. Only part of the total amount of accumulated charge can be rapidly released to the primary winding 41 of the ignition coil 40.

Of course, in other words, in a range where sufficient discharge energy can be obtained in the secondary winding 42 of the ignition coil 40 even at the time of low load, the pulse width of the ignition signal Vd of the single-shot pulse voltage waveform. In addition, as long as it is within the above range, the narrower the pulse width is, the more the electric charge stored in the energy storage capacitor 30 can be saved. It is possible to generate a pulse voltage waveform of

That is, when the operating state determination unit 92 determines that the internal combustion engine is under a load of a predetermined magnitude or more and is in a high load state, the ignition signal creation unit that was validated as described above.
93 is invalidated, and one of the ignition signal creation unit 94 and the ignition signal creation unit 95 is enabled according to the determination result of the rotation speed determination unit 91.

Now, the determination in the operating state determination unit 92 is such a determination as a high load state, and the determination in the internal combustion engine rotational speed determination unit 91 is a low rotational speed state that is equal to or lower than a predetermined threshold rotational speed. Then, only the ignition signal generating unit 94 is effective, and the ignition signal Vd is used as a part (a) in FIG.
As shown in, a pulse voltage waveform continuously generated a plurality of times is created, and this is given to the voltage control insulated gate type switching element 50.

Even in such a plurality of pulse voltage waveform groups, the pulse width of each pulse may be the same as the pulse width of the one-shot pulse voltage waveform in the portion (a) in FIG. 3 described above. Then, when the ignition signal Vd, which is a pulse voltage waveform that is continuously generated a plurality of times, is given to the switching element 50, the switching element 50 naturally responds to this and repeatedly turns on and off a plurality of times. As a result, the spark plug P also has a plurality of continuous discharge sparks due to the high voltage waveform repeatedly appearing in the ignition coil secondary winding 42.

Then, as a result of such continuous ignition a plurality of times, it is possible to obtain effective ignition performance especially at high load. Conversely, conversely, the capacity of the energy storage capacitor 30 is selected to be an appropriate size, and By selecting the pulse width of the pulse voltage waveform to be an appropriate thinness, the charge stored in the energy storage capacitor 30 can be divided and used several times, and multiple discharge sparks can be obtained per ignition operation. it can.

As a matter of course, the pulse interval of each pulse voltage waveform is set to be longer than or equal to the time required for surely completing each discharge in the continuous discharge operation. Further, in FIG. 3, for simplification, only the pulse voltage waveforms of three shots are continuously shown, but according to the experiment of the present inventor, an energy storage capacitor 30 of about several tens of μF is selected. When the pulse width of each pulse voltage waveform forming each ignition signal Vd is set to about several μs,
The electric charge stored in the energy storage capacitor 30 is hardly consumed by the discharge operation only once over the several μs, and therefore, the continuous discharge can be performed over a considerable number of times.

As described above, according to the present invention, even when the internal combustion engine has a high load, particularly when the engine is at a relatively low rotation speed, the spark discharge in the spark plug is repeated a plurality of times per unit ignition time, so that the ignition energy is increased. However, in the present invention, even in the same high load state,
When the engine is in a relatively high speed state, the discharge energy is not increased by the number of discharges, but is increased by the peak value of the discharge current and the discharge duration time.

In other words, when the engine is in a relatively low speed state, there is a certain time delay from the start of ignition of the engine until the actual explosion, so it is possible to fly discharge sparks with the spark plug many times during that time. In fact, this greatly improves the ignitability, but as the engine speed increases considerably, the time from the start of ignition to the explosion becomes very short, so many times during that time. It becomes difficult to repeatedly obtain an effective spark discharge. For example, if the discharge is configured to be repeated the same number of times as in the relative low rotation state, the discharge in the rear is completely wasted.

From this, when the operating state determination unit 92 determines that the engine is in a high load state, if the engine speed determination unit 91 detects a relatively high engine speed state, then only the ignition signal generation unit 95 is effective. From there, as shown in part (c) in FIG. 3, a pulse voltage waveform having a pulse width wider than the pulse width in the steady state, though it is a single pulse voltage waveform, is used as the ignition signal Vd. Created and output.

As a result, the switching element 50 also remains on for a relatively long time, during which the amount of charge supplied from the energy storage capacitor 30 increases considerably. In response to this, the secondary current waveform obtained in the secondary winding 42 of the ignition coil 40 is also high in its peak and long in duration as also shown in FIG. Therefore, appropriate high discharge energy can be applied to the spark plug under high load and high rotation.

The capacity discharge ignition device of the present invention has been described above with reference to an embodiment thereof, but various modifications can be made without departing from the spirit of the present invention. For example, in the illustrated embodiment, the ignition signal Vd has a pulse voltage waveform that transits in the positive direction between a significant value and substantially the ground potential, but it goes without saying that the polarity of the voltage-controlled insulated gate switching element used is Depending on the polarity of the power source, it is possible to establish a relationship in which the switching element 50 is turned off when the ignition signal Vd becomes a large absolute value in the negative direction, and turned on when approaching the ground potential from the negative region side. .

[Effects] According to the present invention, it is possible to provide a capacitive discharge ignition device that operates in an extremely rational manner.

That is, when the internal combustion engine is under a low load (steady state), the voltage-controlled insulated gate switching element is turned on only once per unit ignition time for a short time to store the accumulated charge in the energy storage capacitor. Since it is possible to discharge only the required amount, the conversion efficiency of the ignition coil can be increased, while the internal combustion engine has a high load,
When the engine is in a low speed state, the relative ignition energy is increased by continuously generating a plurality of discharge sparks per unit ignition time, so that the ignitability in such a state can be improved. .

Furthermore, even when the internal combustion engine is in the same high load state, especially when it is in a high rotation state, the plurality of spark discharges at the time of low rotation as described above, which may be wasted or may be disabled, is stopped, and By turning on the voltage control insulated gate type switching element for a long time,
Since the ignition energy is increased by increasing the discharge current, the increased ignition energy can be optimally given to the ignition plug of the internal combustion engine under such a high load and high rotation condition, and the ignition performance is also improved. Can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of a circuit portion in an embodiment of a capacity discharge type ignition device constructed according to the present invention, and FIG. 2 is an ignition signal processing circuit in the first illustrated circuit. FIG. 4 is an explanatory view showing a relationship with each detection circuit around it, and FIG. 3 is an explanatory view showing a relationship between an ignition signal emitted from an ignition signal processing circuit in the first illustrated circuit and an ignition coil secondary current, FIG. 4 Is an explanatory diagram showing a general circuit configuration example that can be used as a DC-DC converter in the first illustrated circuit, and FIG. 5 is a voltage-controlled insulated gate type that is connected in series to the ignition coil primary winding in the first illustrated circuit. It is explanatory drawing which shows the alternative example of a switching element. In the figure, 10 is a battery, 20 is a DC-DC converter, 30 is an energy storage capacitor, 40 is an ignition coil, 41 is an ignition coil primary winding, 42 is an ignition coil secondary winding, 50 is a switching element, and 60 is an operating element. State detection circuit, 70 engine speed detection circuit, 80 ignition timing detection circuit, 90 ignition signal processing circuit, 91
Is an engine speed determination unit, 92 is an operating state determination unit, 93, 94 and 95 are ignition signal generation units, and P is an ignition plug.

Claims (1)

[Claims] 1. A switching element is turned on by an ignition signal emitted from an ignition signal processing circuit based on an ignition timing signal from an ignition timing detection circuit, and an electric charge accumulated in an energy storage capacitor is discharged to a primary winding of an ignition coil. A high-voltage is obtained in the secondary winding of the ignition coil, and the high-voltage causes a spark spark to be discharged to an ignition plug for a capacity discharge ignition device for an internal combustion engine; the switching element is turned on by a voltage signal. One composed of a voltage-controlled insulated gate type switching element capable of controlling OFF at high speed; an engine speed detection circuit for detecting the speed of the internal combustion engine, and an operating condition detection for detecting a load condition of the internal combustion engine. A circuit is provided; the ignition signal processing circuit is configured by a determination unit and an ignition signal generation unit; and the determination unit is the operation state detection circuit. Based on the detection signal, the internal combustion engine is judged to be in a relatively low load state or a high load state, and based on the rotation speed detection signal from the engine rotation speed detection circuit, A determination is made as to whether the internal combustion engine is in a relatively low rotation state or a high rotation state; when the internal combustion engine is in a relatively low load state based on the determination of the determination section, A single pulse voltage waveform having a relatively narrow pulse width is created as an ignition signal, and when the internal combustion engine is in a relatively high load state and a relatively low rotation state, the ignition signal is generated. As a result, a plurality of pulse voltage waveforms, each of which has the above-mentioned relatively narrow pulse width but is repeatedly generated a predetermined number of times, are created. Furthermore, the internal combustion engine is in a relatively high load state, and a relatively high rotation speed is obtained. Ignition when in the state Generating a single-pulse voltage waveform with a relatively wide pulse width as a signal;