JP2657941B2 - Overlap discharge type ignition device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition device for an internal combustion engine mounted on a motor vehicle, and more particularly to an improvement of an overlap discharge ignition device.

[0002]

2. Description of the Related Art Recently, a so-called lean burn engine (lean burn engine) having an extremely low air-fuel ratio has been adopted as an internal combustion engine mounted on a vehicle. However, this type of engine is not so efficient,
A high energy type ignition device is required. Therefore, a lap discharge type ignition device has been proposed in which a high-voltage output of a DC-DC converter is superimposed on an output of a secondary side of an ignition coil generated by a classic current interruption principle.

FIG. 6 shows an example of a typical circuit or an example of a basic configuration of such a conventional lap discharge type ignition device, and FIG. 2 for explaining the operation of the device of the present invention later. For comparison, the left half shows signal waveforms, current, and voltage waveforms of the main part of the conventional device. Referring to these drawings, based on a signal from an ignition timing sensor 11 that informs the ignition timing of a cylinder, such as a crank angle sensor, the ignition control circuit unit 12 in the current cutoff circuit section 10 first determines the ignition timing. Shortly before, the ignition signal Sf is changed from the previous low level “L” to the high level “H”, so that the power switching element built in the current interrupting unit 13 (in the case of the drawing, simply with a single bipolar transistor Q1 only) (Shown) is conducted, a primary current flows from the vehicle-mounted battery 16 having the output voltage Vb to the primary side of the ignition coil 14, and energy is accumulated in the primary winding of the ignition coil 14.

When the ignition control circuit unit 12 determines that the ignition timing of the cylinder has been reached based on the output from the ignition timing sensor 11, the ignition control circuit unit 12 issues an ignition signal Sf
To a low level. This is a significant timing as the ignition signal Sf, whereby the power switching element Q1, which is an output stage built in the current interruption unit 13, is turned off, and the primary current of the ignition coil is rapidly interrupted, so that High voltage occurs.

[0005] In the case of a classic ignition device based only on the current interruption principle, the secondary high voltage of the ignition coil 14 breaks the discharge gap of the ignition plug 15 and generates a discharge spark.
A gradually decreasing discharge current flows through the spark plug 15. In FIG. 2, the discharge current component generated only by the current interruption is indicated by a virtual line with respect to the total discharge current i _O obtained by the overlap discharge described below. However, in the case of the lap discharge type ignition device considered in this document, the discharge current component due to such current interruption is based on the booster circuit output voltage from the DC-DC converter unit (lap discharge circuit unit) 20. The output current is also superimposed, and is a current having a waveform indicated by a solid line as the discharge current i _{O in} FIG. That is, the ignition signal Sf from the ignition control circuit unit 12 is
8, through a signal input terminal T _2, DC-DC converter unit 2
0, especially to the built-in overlap discharge control circuit 21. In the overlap discharge control circuit 21, the ignition coil 14 described above is used.
The same ignition signal that determines the primary current interrupt timing
The falling timing of Sf is taken as a significant timing, and the oscillation circuit 22 is oscillated for only a predetermined time ts from this time, as indicated by a connection line A in FIG. Element (in the case shown, MOS
FET) Q2 is choppered at a predetermined cycle (at a predetermined duty ratio), and the primary current of the step-up transformer 23, one end of which is connected to the battery voltage Vb, is interrupted at the predetermined duty ratio. To generate a high-pressure output on the secondary side.

In this document, the duty ratio of the oscillation output of the oscillation circuit 22 is described as on-duty. That is, as shown in an enlarged part of the oscillation output of the oscillation circuit 22 in FIG.
Assuming that the time during which the oscillation waveform rises to a significant level for turning on the switching element Q2 is t _O , the duty ratio is treated as on duty t _O / tf. There are other ways of expressing the duty ratio, but since they can be rewritten in the above-mentioned notation in the end, the following description can be applied almost as it is. Of course, the oscillation circuit 22
If the oscillation frequency is constant, the on-duty t _O /
As tf is set larger (as the switching element ON time t _O within the cycle tf is set longer), the secondary-side output voltage of the step-up transformer 23 increases.

In any case, as described above, the DC-DC
The output current based on the high-voltage output voltage generated by the booster circuit in the converter unit 20 is added with the same polarity to the discharge current generated by the current interruption principle via the diode DL,
As a result, the total discharge current i _O flowing through both ends of the ignition plug 15 does not gradually decrease as compared with the case of the imaginary line without using the DC-DC converter unit 20, and is larger by a certain time ts for a predetermined time ts. It is extended as it is. Further, the spark plug voltage V _P is increased in general the absolute value at the time of initial discharge initiation by current interruption principle to a 2 to 3 kV, the ignition plug 15
When the discharge is stable and stable, the absolute value is almost 50
Stabilizes at about 0V. Conversely, to satisfy this,
The output voltage at the output terminal of a DC-DC converter is generally
Set from 1.5KV to about 2KV or more.

The capacitor Cs forms a smoothing circuit in combination with a rectifier diode DL for adding and superimposing the high-voltage output current of the DC-DC converter unit 20 on the current interruption discharge current with the same polarity and superimposing the same. The smoothing capacitor Cs also
In addition to its original purpose of smoothing, it also has a function of quickly passing a transient rising component of a discharge current caused by current interruption. However, after the discharge current i _O as an output current from the DC-DC converter unit 20 has settled in a DC manner at, for example, about 50 mA, the discharge current Io does not pass through the smoothing capacitor Cs, and the secondary winding of the ignition coil 14 A superimposed discharge current flows from the wire through a path through the diode DL, the secondary winding of the step-up transformer 23, the ground, and the ignition plug 15. In addition, the DC-DC converter unit 20, which is generally formed as a single unit or as a module as a component, may be grounded through a dedicated grounding cable, but usually, a metal part of a case of the unit is used. Often grounded. These points also apply to an ignition device to which the present invention described later is applied.

[0009]

However, in the above-mentioned conventional example, when the internal combustion engine is rotated at a high speed, a so-called "blowing out phenomenon" may occur. That is, under the high-speed rotation of the engine, the fluctuation of the air flow in the combustion chamber becomes large, so that the ions between the spark plug discharge gaps may be blown off.Therefore, the discharge current Io is intermittent or interrupted and the discharge spark becomes unstable. It will disappear. Such phenomena are, for example, common parameters regarding the lap discharge energy in the conventional lap discharge type ignition device, setting the booster circuit output voltage to about 2 KV, the lap current to about 50 mA, and the lap time ts to about 2 to 4 mS. This was a common problem when In order to prevent this, for example, the booster circuit output current (superimposed current) is increased to about 100 to 130 mA, so that the booster circuit output voltage has to be increased to, for example, 3 KV or more.

[0010] However, in order to prevent the above-described blow-out phenomenon from occurring in the internal combustion engine, particularly in a high speed region, the DC-DC
The method of simply increasing the output voltage of the converter unit 20 is too wasteful as an ignition energy increasing method for an internal combustion engine that is often operated in a low-speed rotation range rather than a medium-speed rotation range. Output voltage as described above
The DC-DC converter unit 20 with 3 KV, output current of 100 to 130 mA, etc. can be converted to output power of 300 to 400 W. Is too much burden on the battery 16 mounted on the vehicle, which is not desirable. The intention to reduce energy by lean-burn engines has also diminished.

Further, as the internal combustion engine rotates at a higher speed, the ignition interval for each cylinder also becomes shorter.
Oscillation signal output time from oscillation circuit 22 to determine ts
ts (in the case of the drawing, the time ts and the overlapping discharge duration are treated as substantially the same, and even if they are not exactly the same, they are very close values in a proportional relationship, so this is a sufficiently general explanation) Is fixed, so that the time ts completely falls within the ignition interval between one ignition turn and the next ignition turn at the time of high-speed rotation of the engine (the ignition operation per ignition The time ts had to be set relatively short so as to ensure that it was completed within. Therefore, the overlap discharge duration ts below the middle speed range
This was not possible even though taking longer times could increase the lap discharge energy, or it might be desirable.

In addition to the performance problem, the conventional configuration shown in FIG. 6 has the following device configuration problem. That is, the overlap discharge circuit unit 20 shown as the DC-DC converter unit 20 in the conventional device is often literally made as one unit in one device module, but when this is incorporated in a vehicle, the battery 16 is connected to the battery 16. Needless to say, the power supply wiring 19 is required, and in addition, as shown by reference numerals 17 and 18 in FIG. 6, connection work of at least two wirings is indispensable. The wiring indicated by reference numeral 17 is a high-voltage output terminal T ₁ of the DC-DC converter unit 20.
And one end of a secondary winding of the ignition coil 14, and another wiring indicated by reference numeral 18 is an output terminal of an ignition signal Sf of the ignition control circuit unit 12 and a DC-DC converter. a wiring for connecting the signal input terminal T ₂ of the overlapping discharge control circuit 21 in the unit 20.

Therefore, for example, in the case of a six-cylinder vehicle, which is not uncommon these days, it is necessary to perform a total of twelve wiring work, that is, six wirings for output of the DC-DC converter unit and six wirings for receiving input signals. I do. Such troublesome wiring work has been another disadvantage of the conventional overlap discharge type ignition device.

Furthermore, if it is such a wiring relationship, for example, wiring to the signal input terminal T ₂ is connected correctly, the operational error or other causes, only the output lines of the DC-DC converter unit 20 is disengaged If they were, as will become a high voltage is generated in the high-voltage output terminal T ₁ which is exposed, it is also dangerous.

The present invention has been made to improve various drawbacks of the conventional overlap discharge ignition device as described above, and at least according to the operating condition of the internal combustion engine,
In order to prevent the blow-out phenomenon, a necessary and sufficient overlapping discharge energy can be given at each time, but the first object is to prevent wasteful consumption of large electric power until unnecessary time.

The present invention also avoids the inconvenience of having to set the overlap discharge duration not fixed as in the prior art, that is, to set the overlap discharge duration to a considerably short time in accordance with the maximum rotational speed of the internal combustion engine. It is another object of the present invention to variably control the overlap discharge duration so as to be appropriate according to the rotation speed of the internal combustion engine.

Further, according to the present invention, when the lap discharge circuit section of the lap discharge type ignition device is particularly unitized separately from the current cutoff circuit section as in the DC-DC converter unit 20 described above, the mounting and wiring work Simplify
Another object is to ensure safety by preventing a high voltage from being generated even if the high-voltage output terminal is accidentally exposed.

[0018]

According to the present invention, first, in order to achieve the above-mentioned first object, the discharge spark generated in the ignition plug is prevented from blowing out even if the engine speed is increased.
In order to increase the value of the output voltage on the secondary side of the step-up transformer, the microcomputer performs program control on the relationship between the engine speed and the on-duty of the switching element that choppers the primary current of the step-up transformer. A basic control mode is to variably set an appropriate value according to the number of rotations.

In addition, the present invention further provides an ignition device having the following correction function, ie, a current for detecting the actual magnitude of the lap discharge current flowing for a predetermined time for each ignition. A value detection circuit is provided, and for each ignition cycle, a reference current value which is an overlap discharge current value to be obtained at the time of on-duty set by the above-described program control by the microcomputer according to the engine speed at that time, If the microcomputer recognizes that the current value actually detected by the current value detection circuit is lower, the microcomputer creates and stores correction data related to the on-duty set by the above-described program control, The same or almost the same engine speed as the ignition time for which the correction data was created for the ignition times after the next time At this time, a new on-duty is set by adding a correction based on the stored correction data to the on-duty to be set by the program control, and control is performed so as to increase the overlapping discharge current value of the ignition time. An ignition device is proposed. As another aspect of the ignition device of the present invention configured as described above, as a result of the comparison between the two current values, while the basic control aspect described above is common, it is actually detected. If the microcomputer recognizes that the current value is higher than the reference current value, the microcomputer creates and stores correction data relating to the on-duty set by the above-described program control, and stores the correction data for the next and subsequent ignitions. In an ignition cycle in which the number of revolutions of the engine is the same or almost the same as the number of revolutions of the ignition in which the correction data was generated, the correction data stored for the on-duty to be set by the program control is stored. A new on-duty is set by adding a correction based on the above, and an apparatus for controlling so as to reduce the overlapping discharge current value of the ignition time can be proposed. In addition,
In this document, the expressions "low" to "small" and conversely, "high" to "large", including those in the claims, are comparative expressions in absolute values.

According to the present invention, as a lap discharge type ignition device having a correction function in the same manner as described above, the microcomputer determines that the actually detected current value is smaller than the reference current value within a predetermined time during which the discharge current continues. In accordance with the time rate that is lower than the above, the correction data relating to the on-duty set by the program control is created and stored, and the engine rotation speed of the next ignition time and the subsequent engine rotation speed produce the correction data. At the ignition time equal to or substantially equal to the engine speed of the ignition time, the microcomputer sets a new on-duty by adding a correction based on the stored correction data to the on-duty to be set by program control. In addition, an ignition device that controls so as to increase the lap discharge current value of the ignition cycle is proposed. In the ignition device configured as described above, similarly to the above, the microcomputer determines whether the actually detected current value is higher than the reference current value within the above-described predetermined time, Generates and stores correction data related to the on-duty set by the program control, and sets the same or almost the same engine rotation speed as the ignition rotation for which the correction data was generated for the next and subsequent ignitions. At this time, the microcomputer adds a correction based on the stored correction data to the on-duty given by the program control, sets a new on-duty, and lowers the overlapping discharge current value of the ignition time. Can be expanded to a controlled configuration.

In any of the above-described ignition devices of the present invention, when the microcomputer sets a new on-duty using the correction data and performs control to increase the overlapping discharge current value, the reference current value is also reduced. When the control is performed so as to change the reference current value to a slightly higher value, and conversely, to lower the reference current value, the reference current value can be changed to a slightly lower value.

Further, in the present invention, the voltage value actually obtained on the secondary side of the step-up transformer is replaced with or in addition to the correction processing according to the value of the lap discharge current actually flowing as described above. An overlap discharge type ignition device which performs a correction process in view of the above is also proposed. That is, in the present invention, the microcomputer sets a reference for a high voltage to be obtained on the secondary side of the step-up transformer at the time of the on-duty set by the above-described program control according to the engine speed at each ignition time. If it is recognized that the boost transformer secondary voltage value actually detected by the voltage detection circuit is lower than the voltage value, the correction data relating to the on-duty set by the program control is created and stored, In the ignition times of the next and subsequent ignition times in which the engine speed is the same as or substantially the same as the engine speed of the ignition time for which the correction data was created, the on-duty to be set by the program control is stored. A new on-duty is set by adding a correction based on the correction data that has been used, and the value of the secondary output voltage of the step-up transformer for that ignition time is increased. Suggest ignition device for controlling the so that. In such an apparatus, even when the voltage value actually detected is higher than the reference voltage value as a result of the comparison, the microcomputer creates correction data related to the on-duty set by program control. In the ignition times subsequent to the next time, and the engine speed of the next time is the same or almost the same as the engine speed of the ignition time for which the correction data was generated, the on-duty to be set by the program control is set to the on-duty. On the other hand, it is possible to develop a configuration in which a new on-duty is set by adding a correction based on the stored correction data, and the value of the secondary high voltage of the boosting transformer at the ignition time is reduced.

Further, according to the present invention, when the actually detected voltage value is lower than the reference voltage value, instead of producing and storing the correction data relating to the on-duty set by the program control, An ignition device that creates and stores correction data related to the on-duty set by program control according to the time rate at which the actually detected voltage value is lower than the reference voltage value, and further detects the actually detected voltage value. In the device that creates and stores correction data related to the on-duty set by the above-described program control even when the set voltage value is higher than the reference voltage value,
Alternatively, when the actually detected voltage value is often higher than the reference voltage value, correction data relating to the on-duty set by the program control according to the higher time rate is created. Also proposed is an ignition device for storing the information.

In the case of the igniter having a configuration in which the correction is made in view of the output voltage value actually obtained on the secondary side of the step-up transformer, the microcomputer uses the high-voltage of the step-up transformer secondary side. When the control is performed so as to increase the value, the above-described reference voltage value may be slightly changed to a higher value, and when the control is performed to decrease the value, the configuration may be further modified so as to further control the reference voltage value to be slightly reduced.

The present invention proposes an ignition device that variably controls the "predetermined time" for turning on and off the switching element in accordance with the engine speed in addition to the above-described configurations. That is, in the ignition device according to one aspect of the present invention, the microcomputer performs program control also on the relationship between the engine speed and the predetermined time for operating the switching element, and sets an appropriate time value according to the engine speed at each time. The predetermined time is variably set so that Therefore, the engine speed is relatively low,
When the ignition interval is wide, the operating time of the switching element for each ignition cycle can be extended to prevent the discharge spark from blowing out without increasing the output energy of the step-up transformer. Therefore, when the ignition interval becomes shorter and the ignition interval becomes shorter, the operation time of the switching element can be set shorter so that the overlapping discharge operation for each ignition is completed within the ignition interval.

In the present invention, in addition to the above-described improvement in the function and performance, an improvement in the device configuration as an object in the overlap discharge type ignition device is also proposed. As one of them, according to the present invention, a discharge current generation detection circuit for detecting when a discharge current accompanying a current interruption flows and outputting a discharge current generation detection signal is provided. There is proposed an ignition device that receives an occurrence detection signal and calculates an engine speed at each time in accordance with an interval at which the signal is generated.

Further, according to another aspect of the present invention, when the microcomputer has the above-described discharge current generation detection circuit, the microcomputer receives the discharge current generation detection signal from the circuit, and checks the generation of the discharge current. The present invention also proposes an ignition device that outputs an oscillating signal according to an on-duty set at that time over the above-mentioned predetermined time and thereby causes the switching element to perform an on-off operation directly or to perform an on-off operation via a drive circuit.

As described above, if the discharge current generation detection circuit is provided in the lap discharge circuit section itself, the lap discharge circuit can be synchronized with the ignition timing without separately receiving an ignition signal from the current cutoff circuit section. Can be operated, the number of wirings required between the circuit and the current cutoff circuit can be reduced. Since no high voltage is generated on the secondary side of the step-up transformer, even if the output terminal portion of the high voltage connected to the secondary side of the ignition coil in the current cut-off circuit is disconnected due to a wiring mistake or the like, there is no problem. High voltage can be prevented from being generated, and safety is enhanced.

[0029]

FIG. 1 is a schematic circuit diagram showing a preferred embodiment of an overlap discharge type ignition device according to the present invention. For the sake of clarifying the comparison with the conventional example shown in FIG. 6, even in the overlap discharge type ignition device according to the present invention, components that do not particularly need to be changed or corresponding components of the conventional device include: The same reference numerals as those in FIG. 6 are used. Therefore, the description of each of the constituent elements can be referred to the above-mentioned parts, unless otherwise specified. In particular, with respect to the current cutoff circuit section 10, the configuration shown in FIG. 6 and other known current cutoff circuit sections need not be substantially changed. However, in this embodiment, it is desirable that the ignition signal Sf from the ignition control circuit unit 12 need not be taken into the overlap discharge circuit unit 30, which is necessary in the conventional example of FIG. the indicated line (reference numeral 18) and the terminal T ₂ are has become unnecessary.

However, in the overlap discharge circuit section 30 of the present embodiment, the functions corresponding to the overlap discharge control circuit 21 and the oscillation circuit 22 in the conventional example shown in FIG. In addition, functions specific to the present invention are also realized by the microcomputer 31 as described below.

In order to supply necessary data to the microcomputer 31, a current detecting circuit is provided in the lap discharge circuit section 30.
34, a voltage detection circuit 35 in this preferred embodiment.
Is also provided. Further, the current detection circuit 34 in this preferred embodiment includes a discharge current generation detection circuit having an operational amplifier 37 which is a buffer amplifier connected in a voltage follower and a current detection resistor Rd, a comparator 36, and resistors R1 and R1.
R2, and a discharge current value detection circuit for detecting the magnitude (value) of the discharge current actually flowing in the secondary discharge path of the ignition coil 14 including the ignition plug 15 in series. Made up of The current detection resistor Rd is in principle a spark plug
Although it may be anywhere in the discharge path of the discharge current including 15, in the case of the drawing, the secondary winding of the step-up transformer 23 which is the output stage of the step-up circuit (DC-DC converter) 33 and the ground are connected. This position is relatively safe in terms of potential, and as will be described again later, when the lap discharge circuit unit 30 is unitized or modularized as one component, This is a good position to pre-install in

The voltage across the current detection resistor Rd is applied to the positive-phase input of the buffer amplifier 37 while the maximum voltage value of the current detection resistor Rd is limited to a value that can be handled by the current detection circuit 34 by a Zener diode. The output voltage Vd of the buffer amplifier 37 that appears in response to the voltage is input to the microcomputer 31. As a result, in this preferred embodiment, the overlap discharge circuit section 30 does not need to receive the ignition signal Sf from the ignition control circuit 12 in the current cutoff circuit section 10, and the voltage across the current detection resistor Rd reaches a predetermined voltage. The ignition timing,
Alternatively, the microcomputer 31 can recognize and determine the time when the superimposition discharge current starts to be superimposed, and start the operation. In the right half of FIG. 2, starting from this point, signal waveforms, currents, and voltage waveforms which are convenient for explaining the operation of the apparatus of the present invention shown in FIG. 1 are shown. Hereinafter, the overlap discharge operation will be described with reference to this.

Based on a signal from an ignition timing sensor 11, such as a crank angle sensor, which informs the ignition timing of a cylinder, the ignition control circuit unit 12 in the current cutoff circuit section 10 changes the ignition signal Sf to a high level shortly before the ignition timing. As a result, the primary current starts flowing through the primary winding of the ignition coil 14 via the current interrupting unit 13. In the case shown in the figure, the current cutoff unit 13 is simply shown with only a single bipolar transistor Q1, but it may actually be a combination circuit including a plurality of transistor groups, and may be replaced with a bipolar power transistor. In some cases, a field effect type power switching element is used. Rather, the circuit part involved in this current interruption does not have to be particularly modified by the present invention, as described above, and may be arbitrarily assembled according to existing technology. . Therefore, its operation is well known, and the ignition coil 14 is operated as described above.
When the primary current i1 is flowing through the ignition timing sensor
Based on the output from 11, the ignition control circuit 12 determines the ignition timing of the ignition plug 15 attached to the illustrated cylinder,
The ignition control circuit 12 lowers the ignition signal Sf to a low level. This is a significant timing as the ignition signal Sf, whereby, as shown in FIG. 2, the current interrupting unit 13 rapidly interrupts the primary current i1 of the ignition coil 14 (turns off the power switching element Q1 in FIG. 1), As a result, a high voltage Vp is generated on the secondary side of the ignition coil, so that the discharge gap of the ignition plug 15 is broken, and a discharge current flows through a discharge path including the ignition plug 15 in series while generating a discharge spark in the gap.

However, in the ignition device of this embodiment, one end of the ignition coil (the end opposite to the end connected to the ignition plug) which is normally dropped to the ground in the case of a mere current interruption type ignition device is connected. connected to a terminal T ₁ of the overlapping discharge circuit 30, between the ground and the terminal T _1, the rectifier diode DL, the step-up transformer secondary winding to the terminals T ₁ side and the anode, a current detection resistor Rb
Are interposed in series. Further, a smoothing capacitor CS is connected in parallel between both ends of a series circuit portion of the rectifier diode DL and the secondary winding of the boost transformer 23 in the booster circuit 33.

With the above configuration, the discharge current based on the principle of current interruption by the above-described current interruption circuit section 10 is applied to the current detection resistor provided in the lap discharge circuit section 30 in this embodiment.
Since Rd also passes, a voltage drop occurs across the resistor.
The detected voltage is supplied to the microcomputer 31 via the buffer amplifier 37 as a voltage signal Vd in a buffered relationship with the discharge path. Therefore, in the microcomputer 31, the discharge current is schematically represented by a threshold in FIG.
The input voltage value Vd is compared with the voltage value corresponding to the converted voltage when the voltage exceeds the predetermined value indicated by Ith, and the input voltage
When Vd exceeds the corresponding voltage of the threshold value Ith, it is determined that the current output start timing for the lap discharge has occurred, and the oscillation signal
Start output of So. In other words, in the ignition device of this embodiment, instead of receiving the ignition signal Sf from the current interrupting circuit unit 10 and starting the operation for each ignition time as in the conventional device, the ignition device uses the connection line B in FIG. As shown, the lap discharge circuit section
Using the discharge current generation detection circuit provided in 30 itself, the microcomputer 31 determines the start point of the overlap discharge operation by itself.

An oscillation signal generated by the microcomputer 31
As shown in FIG. 2, So is a booster circuit composed of a power MOSFET as shown partially enlarged in FIG.
33 is a pulse continuous waveform in which a high level and a low level alternately continue to turn on and off the switching element Q2 in 33, and the on-duty is the reciprocal of the frequency t _O during which the switching element Q2 is turned on. It can be expressed by the value t _O / tf divided by the period tf, and the duration of the signal So (the output time of the oscillation signal from the microcomputer 31)
Is indicated by ts. In the case of the illustrated embodiment, the oscillation signal So is given to the switching element Q2 via a driving circuit 32 called a driver, whereby the switching element Q2 is turned on at a predetermined on-duty for a time ts.
When turned on and off, the primary current of the step-up transformer 23 having one end connected to the battery voltage Vb is choppered according to the on-duty, and a high voltage _VO is generated on the secondary side as shown in FIG. This high voltage V _O is added by the rectifier diode DL with the same polarity as the polarity of the secondary high voltage (ignition plug voltage Vp) of the ignition coil 14 in the current cutoff circuit section 10, and as a result, the output of the booster circuit The output current based on the high voltage V _O is superimposed additively on the discharge current previously generated by the current interruption principle, and a total discharge current Io is also obtained as shown by a solid line in FIG. The duration, that is, the duration ts of the discharge spark, corresponds to the output time ts of the oscillation signal So from the microcomputer 31.

However, in the conventional lap discharge type ignition device, when the rotational speed of the internal combustion engine increases, the discharge spark generated between the discharge gaps of the spark plug blows out due to the fluctuation of the air flow in the cylinder. It has already been mentioned that it may be done. On the other hand, to prevent this, simply increasing the output power of the booster circuit would greatly waste power consumed by the booster circuit below the medium-speed rotation range, which occupies most of the time during engine operation. Was. Therefore, in the present invention, in order to solve such inconvenience, as the most basic configuration,
The microcomputer 31 controls the on-duty of the oscillation signal So and the on-duty related to the on / off operation of the switching element Q2 by program control so that the output energy of the booster circuit 33 is controlled to be large when necessary, and to be controlled small otherwise. .

That is, as shown in FIG. 3B, the microcomputer 31 increases the on-duty of the oscillation signal So as the rotational speed of the internal combustion engine increases. , On duty displayed as%
If expressed as {(t _O / tf) × 100}, 80 during idling operation
20% at 0rpm and 50% at 6000rpm, during which the program control follows a monotonically increasing linear function. Therefore, when the engine speed is 6000 rpm or more, for example, the boosting transformer of the boosting circuit 33 is set so that the output power of the boosting circuit 33 becomes the maximum output power from 300 W to 400 W or more.
By determining the capacity of the switching element 23 and the switching element Q2, and operating with such a large power, it is possible to prevent the discharge spark blowing phenomenon, but instead of always operating with such a large power, As can be seen in normal vehicle driving conditions, below the engine middle speed range, which covers most of the operating time, the booster circuit 33 according to the low engine speed.
Output power can be kept at a small enough value that does not cause the discharge spark blowing out phenomenon at the rotation speed.

The present invention is not limited to the program control algorithm itself. Among the methods employed in this type of information processing technology,
Any suitable one may be selected. For example, ROM or EPRO built in or external to the microcomputer 31
The microcomputer 31 substitutes the value of the internal combustion engine speed at each time into the function formula in accordance with the linear function formula stored in M (not shown), thereby obtaining a curve (straight line) shown in FIG. ), The on-duty of the oscillating signal So at each time may be determined, and the on-duty is continuously changed in an analog manner with respect to a change in the internal combustion engine speed. Rather, it divides the maximum rotational speed range of the engine into several parts, such as what percentage from one rotation to some higher rotation, and what percentage from the higher rotation to some rotation. A digital or step-like program control curve in which an appropriate on-duty is associated with each of the rotation speed ranges described above may be used. In the latter case, instead of reading and calculating the function formula, it is prepared in advance for each rotation speed range, and corresponds to the engine speed at each time from the on-duty lookup table stored in ROM or EPROM. May be read and used.

Further, in this preferred embodiment, the microcomputer 31 controls the program for the output time of the oscillation signal So generated by the microcomputer 31 and the duration ts of the overlap discharge current Io.
That is, in the example shown in FIG. 3A, the oscillation signal output time (overlap discharge duration) ts is about 5.5 mS at 800 rpm during idling operation, about 4.5 mS at 1000 rpm, about 2.5 mS at 3000 rpm, and 3000 rpm. About 1.8mS, about 4000mS at 4000rpm,
Each corresponding data is stored in the microcomputer's RO so that the speed is about
M or stored in an external EPROM, and the duration ts at each rotation speed between the above-mentioned rotation values is calculated by linear approximation and interpolated. Also in this case, there is an interpolation method outside, a curve approximation is also possible, and as described above with respect to the on-duty, the maximum rotational speed range of the engine is divided into several parts, and each divided rotational speed range is Processing using a look-up table in which an appropriate duration ts is written in advance is also possible.

In any case, the output time ts of the oscillation signal is fixed to a constant value irrespective of the internal combustion engine speed, as in the prior art.
As a result, such processing in this embodiment is extremely desirable as compared with the case where the overlap discharge current duration ts is always fixed. When the ignition interval becomes short due to the engine being in the high-speed rotation range, the duration ts of the lap discharge current is also shortened to ensure that the ts falls within the ignition interval. The decrease can be compensated for by an increase in the lap discharge current Io due to an increase in the on-duty by the above-described program control.On the other hand, as the engine speed decreases, the ignition interval also increases. Since the overlap discharge energy determined by the power-time product can be increased as much as necessary in that range, the value of the on-duty variably set by the above-described program control regarding the on-duty is not increased so much. It is possible to well prevent the discharge spark from blowing out while keeping the power consumption of the battery 16 low.

As described above, in the overlap discharge type ignition device to which the present invention is applied, the on-duty of the switching element Q2 is
program control with respect to t _O / tf, and more preferably the operating time ts of the switching element per ignition cycle
By controlling the program, the power consumption of the battery can be reduced while the resistance to the blowout phenomenon is high.

However, for example, not only in the case where the vehicle type is different and the internal combustion engine itself is different, there is a difference in characteristics due to the difference in conditions in each cylinder, etc., even for the same type of internal combustion engine. Even if the switching element Q2 is driven with an on-duty corresponding to the current internal combustion engine rotational speed determined by the program control by the above, the value of the overlap discharge current Io may not always be an optimum value for the engine. Therefore, in the ignition device of the present invention, as can be seen in the embodiment described here, it is possible to correct for this.

For this purpose, first, in the current detection circuit 34,
Outside the discharge current generation detection circuit including the buffer amplifier 37 and the current detection resistor Rd described above, the magnitude of the overlap discharge current Io actually flowing in the discharge path is detected and input to the microcomputer 31. Therefore, the comparator 36 and the voltage dividing resistors R1 and R2
And a current value detection circuit having the following. In this embodiment, the current value detection circuit further uses the current detection resistor Rd and a voltage follower-connected buffer amplifier 37 that outputs the voltage between both ends while buffering the voltage with respect to the discharge path as one component. And
In this case, the positive-phase input of the comparator 36 includes the current detection resistor Rd.
After being converted to the corresponding voltage value and detected, the output voltage Vd buffered by the buffer amplifier 37 is applied. On the other hand, the negative-phase input is supplied from the microcomputer 31 via the voltage dividing resistors R1 and R2. A reference voltage Vr1 having a value corresponding to the magnitude of the lap discharge current Io as an expected value that will be obtained at the time of the on-duty determined by the microcomputer 31 based on the program control according to the internal combustion engine speed is applied. I have.

Here, an example of a waveform of the overlap discharge current Io based on the actual discharge waveform is represented by a converted voltage waveform (corresponding to the waveform of the voltage Vd) across the current detection resistor Rd as shown in FIG.
This figure faithfully traces the actually measured converted voltage waveform (the maximum value that occurs at the beginning of the current interruption discharge is limited by a zener diode in parallel with the current detection resistor Rd). As you can see, in some cases,
The actually obtained lap discharge current Io (converted voltage value Vd) fluctuates up and down with respect to the reference current value (reference voltage value Vr1) even during the discharge duration ts per ignition cycle. Therefore, the output voltage signal of the comparator 36 provided in this embodiment is
V _X is a high level “H” as a binary signal even within the time ts.
, And at a low level "L".

The microcomputer 31 includes a comparator 36
Have received binary voltage signal V _X to output a reference voltage value Vr1 corresponding to the overlapping discharge current value to be obtained when the on-duty set by program control in response to prevailing engine speed, Indeed comparison determines in view of the magnitude relationship between the converted voltage value Vd corresponding to the detected current value to output a binary signal V _X of the comparator 36 by the current value detection circuit, as a result, particularly the preferred embodiment In the example, the time rate at which the converted voltage value Vd corresponding to the actually detected current value is lower than the reference voltage value Vr1 corresponding to the reference current value (in the illustrated example, the output voltage of the comparator 36 depending on the value voltage signal V _X is "L" the sum of the time that is a level discharge duration to a value obtained by dividing the output time ts of the oscillation signal So.), producing a correction data relating to on-duty to be set by a program control And built-in RA Storage means etc. (not shown)
To memorize. The correction data may be data representing the time rate itself, or may be an additional rate for the on-duty to be set by program control according to the time rate.

The engine speed of the next and subsequent ignition turns is the same as the engine speed of the ignition turn for which the correction data was prepared (including cases where the engine speeds are not exactly the same in a strict sense but are substantially the same: Similarly, in the ignition cycle, the microcomputer 31 sets a new on-duty by adding a correction based on the stored correction data to the on-duty to be set in the oscillation signal So for the ignition cycle by program control, Control is performed so as to increase the lap discharge current value of the ignition cycle. For example, when a state occurs in which the overlap discharge current value actually detected over a period equal to or more than half of the discharge duration time ts is smaller than the reference current value, the oscillation signal
The on-duty of So is increased by about 10% or 20% from the value given by the program control corresponding to each engine speed, or the correction increment is increased as the engine speed increases.

When such correction control is performed, better feedback control may be possible if the value of the reference voltage value Vr1 itself is slightly increased. For example, if the on-duty of the oscillation signal So is increased by about 10%, and if the reference voltage value Vr1 is increased by about 5 minutes, etc., the output power of the booster circuit should be increased slightly so as to prevent the blow-out phenomenon. In addition, at the time of the next correction, it can be controlled not to be too high. That is, in the corrected ignition times, the time rate at which the actually detected overlapping discharge current value is smaller than the reference current value is naturally smaller than the previous ignition time before the correction. However, if such a state can be maintained even if the reference voltage value Vr1 corresponding to the reference current value is increased, it can be understood that at least the correction has provided a sufficient overlapping discharge energy, and It is understood that there is no need to uselessly increase the output power, and even if the situation requires correction again, the amount of correction is smaller than when the previous correction was performed, compared to when the reference value was fixed. Since it is supposed, the necessary enhancement of the output power can be kept to a necessary degree.

Of course, the above correction procedure is based on the overlap discharge current value actually detected at the engine speed of the ignition time.
When the time rate at which Io is higher than the reference current value is large, the on-duty of the oscillation signal So determined by the program control corresponding to the engine speed is not greater than the next ignition time. The same can be applied to the case where the correction process is performed in such a way as to reduce this by an appropriate ratio at the same number of revolutions of the engine at the same engine speed.In this case also, the value of the reference voltage value Vr1 can be set slightly lower. it can.

[0050] However, when there is no need to elaborate correction degree described above of view up to the time constant of the output binary voltage signal V _X of the comparator 36 is, for example time overlapping discharge is taking place
The microcomputer 31 compares the reference current value with the actually obtained lap discharge current value Io at one or more predetermined time points during ts, and recognizes only the mere magnitude relation thereof, and According to the result, the microcomputer 31 may generate ignition time correction data for the next and subsequent ignition times and the same engine speed.

However, in the illustrated embodiment, a more accurate correction method is taken into consideration, and a booster transformer is used as a circuit.
This is reflected in the presence of the voltage detection circuit 35 for detecting the actual output voltage V _O of the twenty-third. In other words, a resistor is connected between the anode side of the rectifier diode DL and the ground on the secondary side of the step-up transformer 23.
A voltage dividing circuit by Ra and Rb is inserted. The voltage at this voltage dividing point is supplied from the battery 16 via the power supply wiring 19 to the constant voltage circuit 39 for operating the microcomputer 31 and other active components.
Is applied to the negative-phase input of the comparator 38 while the peak value is clamped to a predetermined voltage value or less by a Zener diode.

On the other hand, the positive input of the same comparator 38
The microcomputer 31 is connected via a voltage divider circuit by R3 and R4.
Provides a predetermined reference voltage Vr2. Its value is
At each ignition time, a high voltage value (expected value) to be obtained on the secondary side of the step-up transformer 23 at an on-duty set by program control according to the internal combustion engine speed at that time is determined by a predetermined voltage division ratio {R4 / (R3 + R4)} (that is, the positive value in this embodiment), and the voltage dividing ratio is a voltage dividing ratio {Rb / (Ra + Rb) of the voltage dividing circuit using the resistors Ra and Rb. } Is the same as The voltage division is performed because the voltage value is too high to exceed the processing capability of the comparator 38 and cannot be directly taken in by the booster circuit output voltage V _O.

FIG. 5 shows a step-up transformer secondary-side high voltage output V _O actually obtained in an experimental example of the illustrated embodiment.
Is shown by solid trace of a voltage waveform obtained by dividing by a predetermined multiplication factor, that is, a voltage dividing ratio {Rb / (Ra + Rb)}. It is shown to rise in the negative direction in accordance with the anode side output of), and with the above configuration, during the discharge duration ts at that time, the output of the comparator 38 includes:
The voltage value across the resistor Rb, which is proportional to the output voltage value V _O that actually appears on the secondary side of the step-up transformer 23, is the reference voltage value Vr2 (FIG. 5).
The output voltage signal Vy, which is a binary signal having a high level when the absolute value is smaller than the absolute value, is obtained.

Therefore, the microcomputer 31 receiving the binary signal Vy from the comparator 38 performs program control according to the current internal combustion engine speed in the same manner as the correction operation based on the current value detection described above. The reference voltage value Vr2 corresponding to the secondary high voltage of the step-up transformer 23 to be obtained at the set on-duty and the voltage across the resistor Rb based on the output high voltage actually obtained on the secondary side of the step-up transformer 23
_{{V O · Rb / (Ra} + Rb)} and the magnitude relation on the basis of the output to a binary voltage signal Vy of the comparator 38 compares the determined results, especially in this embodiment, actually detected voltage value { V _O · Rb / (Ra + Rb)} is smaller in absolute value than the reference voltage value Vr2 (in the case of the figure, the output binary voltage signal of the comparator 38).
(The sum of the time during which Vy is at the “H” level divided by the discharge duration or the output time ts of the oscillation signal So).
Correction data relating to the on-duty to be set by program control is created and stored in a storage means (not shown) such as a built-in RAM. The correction data may be data representing the time rate itself, or may be an additional rate for the on-duty to be set by program control according to the time rate.

In addition, in the ignition times subsequent to the next time, in which the engine speed is the same as the engine speed of the ignition time for which the correction data is generated, the microcomputer 31
Sets a new on-duty by adding a correction based on the stored correction data to the on-duty of the oscillation signal So to be set for the ignition time by program control, and sets a new on-duty. Control is performed so as to increase the overlap discharge current value by increasing V _O. However, as described above, the actually detected overlap discharge current value Io
When the on-duty is changed and corrected based on the above correction data, the actual overlap discharge current value
The correction amount based on the detection of Io is set as the main correction amount, and the correction amount based on the detection of the actual booster circuit output voltage V _O is slightly changed according to the high-level time ratio of the output binary signal Vy of the comparator 38. The correction based on the actual output voltage detection described here may be prioritized, or the correction based on the actual detection of the overlapping discharge current value Io may be supplemented.

In other words, as can be seen in this embodiment, not only the on-duty to be set by program control is corrected based on the actually obtained value of the overlap discharge current Io but also the secondary side of the step-up transformer. Applying correction based on the value of the high voltage V _O actually obtained is excellent in that extremely precise control is possible, but within the practical range, only one of the correction functions is provided. However, there may be enough.

[0057] Incidentally, a subsequent ignition times when making a correction data as described above based on the value of the secondary side high voltage V _O of the step-up transformer 23, the same as in the correction data produced when the ignition times When the on-duty is increased in the ignition cycle that is the engine speed, the value of the reference voltage value Vr2 itself should be set to a slightly higher value. This is the same reason as described above regarding the correction procedure based on the detection of the actual overlap discharge current value Io.

Of course, similarly to the correction procedure based on the current value Io, this is also a step-up transformer secondary-side high voltage V _O.
The above correction procedure based on the its actually detected by the voltage value at the engine speed of the ignition times _{{V O · Rb / (Ra} + Rb)} time rate towards is higher than the reference cell Vr2 If the number is large, the on-duty of the oscillation signal So determined by the program control corresponding to the engine speed is changed by an appropriate ratio in the ignition times at the same engine speed after the next ignition time. The same can be applied to the case where the correction processing is performed in the direction of lowering, and also in this case, the value of the reference voltage value Vr2 can be changed to a slightly lower value.

Similarly, if it is not necessary to perform a detailed correction in consideration of the time rate of the binary signal Vy output from the comparator 38,
For example, the high voltage V _O actually obtained on the secondary side of the step-up transformer is divided by a predetermined voltage dividing ratio with respect to the reference voltage value Vr2 at a predetermined time or a plurality of times during the time ts during which the overlapping discharge is performed. was whether voltage value _{{V O · Rb / (Ra} + Rb)} is high or low is recognized by the microcomputer 31, only by a mere magnitude relationship between the two voltage values which is the recognition result, the microcomputer 31 next time It is also possible to generate correction data of the ignition times of the ignition times and the same engine speed.

By the way, as described above, even when performing the program control having the correction procedure according to the present invention, the microcomputer 31 must know the internal combustion engine speed at each time. Here, in the case where it is not necessary to request an advantage in the apparatus structure described later, and only the effects of the program control including the above-described correction procedure can be enjoyed according to the teaching of the present invention, the microcomputer 31
Can receive data corresponding to the engine speed from the ignition timing sensor 11 or the ignition control circuit 12, for example.
However, as in the illustrated embodiment, when the current detection circuit 34 includes a discharge current generation detection circuit including the buffer amplifier 37 and the current detection resistor Rd, the output voltage signal Vd
By measuring the interval of occurrence of
Can know the engine speed at that time. That is, the time measurement is started from the time when the voltage signal Vd first exceeds at least a predetermined threshold value (for example, a voltage value corresponding to the threshold value Ith in FIG. 2), and the time until the next time is measured. Since the time is the reciprocal of the number of revolutions per minute, the engine speed at that time can be calculated. Therefore,
Since the microcomputer 31 has already calculated the engine speed at that time at least from the second ignition time after the engine has started operation, the microcomputer 31 has already calculated the engine speed at that time. , The correction control in the ignition times can be performed. In order to increase the certainty of taking in the engine speed, for example, about two or three times, when determining the engine speed after repeatedly taking in the ignition interval, the time during that time is taken into account in consideration of the internal combustion engine speed. And the effect of the present invention is not impaired by such a delay.

In other words, conversely, at the time of the first ignition when the engine starts operating, or at each ignition cycle until the microcomputer 31 reliably grasps the engine speed, the microcomputer 31 Cannot know the engine speed. Therefore, as an initial setting, in such a case, the microcomputer is provisionally set as an initial value using an oscillation signal So of an appropriate on-duty or output time ts for the number of revolutions that the engine will reach at the start of engine operation. What is necessary is just to make 31 output.

In the illustrated embodiment, the microcomputer 31 also serves as an oscillation circuit for directly outputting the oscillation signal So. However, an oscillation circuit is provided separately. So on duty t _O /
The microcomputer 31 can be configured to transmit a signal that can control tf or can also control the oscillation signal output time ts as needed, and conversely, the microcomputer 31 can be controlled via the drive circuit 32. Instead, it is also possible to make a change so as to directly drive the switching element Q2 in the booster circuit 33.

As described above, the current detection circuit 34 includes a discharge current generation detection circuit and a detection circuit for detecting an actually generated overlapping discharge current value, and includes a current detection resistor Rd and a buffer amplifier. 37 is a circuit element common to both circuits, and it is desirable that the circuit is downsized and rationalized,
In principle, both circuits may be provided separately. That is, the voltage of both ends of the dedicated current detection resistor inserted in series in the discharge path of the overlap discharge current Io may be supplied to the input of the comparator 36 via the buffer amplifier as necessary. .

As described earlier, if it is only necessary to enjoy the effect based on the program control according to the present invention and further, the effect based on the correction control, the microcomputer 31 sends the ignition signal for each ignition cycle to the microcomputer 31. The signal indicating the time is, for example, a current interruption
You may get it from 10. However, the illustrated embodiment exemplifies a configuration that also eliminates the drawback in the device structure in such a case.

That is, in the conventional apparatus shown in FIG. 6, even if the power supply wiring 19 is omitted, the current interruption circuit section 10 connects to the overlap discharge circuit section 20 in addition to the power wiring (reference numeral 17) for the overlap discharge. On the other hand, the signal wiring (symbol
18) is essential, not only is the number of wires increases, if the signal lines are disconnected even power wiring attached properly, high voltage appears at the terminal T ₁ of the exposed lap discharge circuit, It was thought that danger would be created. However, in the circuit configuration of the device according to the embodiment of the present invention shown in FIG.
As described above, the microcomputer 31 does not need to receive a signal indicating the ignition timing or a signal indicating the rotation speed of the internal combustion engine from the outside, and all of these signals can be obtained in the lap discharge circuit 30. Except for the wiring 19, the electrical connection wiring processing with the current interrupt circuit
Only the high voltage wiring indicated by 17 is required. In other words, the lap discharge circuit unit 30 can be configured as a single unit that also becomes a single module as a component, and the electrical connection with the current interrupt circuit unit 10 is performed by the secondary of the ignition coil 14 in the current interrupt circuit unit. need only provide a terminal T ₁ for connecting the one end of the secondary side of the side of one end and the step-up transformer 23. Therefore, according to the present invention, the number of wires that do not become tedious as the number of cylinders increases can be greatly reduced, and workability is improved. Moreover, if disconnected the wiring, even if exposed to the terminal T ₁ is may touch the hand of a human, such the case, begin discharge current does not flow from the overlapping discharge circuit in the ignition coil 14, the discharge Since the current generation detection circuit never outputs the discharge current generation detection signal Vd, the microcomputer 31 does not confirm the generation of the discharge current, and does not operate the booster circuit 33. possibility that high voltage is generated to the terminal T ₁ at all without a very safe.

In principle, the apparatus according to the present invention shown in FIG. 1 may be provided one for each cylinder of the internal combustion engine. In particular, considering the future, even microcomputers, which are relatively expensive circuit elements in the overlap discharge circuit section, may become extremely inexpensive. It is fully conceivable that even if microcomputers are provided one by one, it would be rather cheaper. However, if it is determined that at least the microcomputer 31 is not one by one per cylinder, it can be shared by all cylinders or several cylinders.
However, in such a case, the microcomputer 31 must know which cylinder the ignition plug 15 to be driven at present. Such a requirement can be satisfied, for example, by the following circuit configuration.

First, as one method, the microcomputer 31 outputs the output of the discharge current generation detection circuit (the output voltage signal Vd of the buffer amplifier 37 in the illustrated embodiment) in the overlap discharge circuit section 30 for each cylinder, respectively. In some cases, a dedicated input is provided. In this manner, as is apparent, it is possible to transmit the oscillation signal So only to the switching element Q2 in the corresponding lap discharge circuit unit 30 only by determining to which input a significant voltage signal Vd is obtained. Can be. This output transmission can be dealt with by providing a dedicated output terminal for each lap discharge circuit unit.

In addition to the program control related to the on-duty of the oscillation signal So and the program control related to the output time ts of the oscillation signal So, the correction procedure based on the detected current value described above is performed. In addition, when performing a correction procedure based on detection of the secondary high voltage of the step-up transformer in addition to or instead of the correction procedure, the output of the current value detection circuit in each lap discharge circuit unit 30 (in the illustrated case, the A dedicated input for receiving the output binary voltage signal V _X ) of the unit 36 is provided, or in addition to or instead of this, the output of the voltage detection circuit (in the case of the drawing, A dedicated input for receiving the output binary voltage signal Vy) of the comparator 38 may be provided.

On the other hand, for example, a microcomputer
In the case where the number of input / output terminals of the microcomputer 31 is limited, a discharge current generation detection signal selectively receiving the output of the discharge current generation detection circuit in each superimposed discharge circuit section 30 is provided to the input interface of the microcomputer 31. Input switching means (not shown) is provided, and if the microcomputer 31 sequentially switches the switching means in a known order, a discharge current generation detection signal from a discharge current generation detection circuit in any one of the lap discharge circuits is provided. Vd
When the microcomputer 31 receives the signal, it is possible to know the overlap discharge circuit unit that has issued the signal Vd according to the switching position of the input switching unit at that time, and based on the information, the microcomputer 31 generates the discharge current that generated the signal. Input switching means (not shown) provided for these may be configured to switch and receive outputs from the current value detection circuit and the voltage detection circuit in the overlap discharge circuit section to which the detection circuit belongs.

In response, the switching element Q2 associated with the cylinder whose ignition timing has reached the ignition timing at that time or its driving circuit 32
On the other hand, even when the common microcomputer 31 selectively outputs the oscillation signal So indicating the on-duty set at each time, output signal switching means is provided for the signal So, and the above can be known. The signal output to the switching element Q2 belonging to the overlap discharge circuit section 30 may be controlled so as to be selected by the microcomputer itself.

[0071]

According to the present invention, the microcomputer program-controls the value of the lap discharge current according to the rotational speed of the internal combustion engine, so that the discharge spark blows out in the combustion chamber according to the rotational speed of the internal combustion engine at that time. Can generate a necessary and sufficient overlapping discharge energy to the extent that no discharge occurs, so that a booster circuit with a large output capacity does not have to be always used at the maximum output, there is no waste of power consumption, and discharge sparks are effectively achieved. Blow-off phenomenon can be prevented.

Further, according to an embodiment of the present invention, the microcomputer controls the duration of the lap discharge in accordance with the current rotational speed of the internal combustion engine. By setting the duration to be longer, the output power of the booster circuit can be made smaller correspondingly, and an ignition device that is more efficient and has high resistance to the discharge spark blowout phenomenon can be provided.

In any case, in the present invention, the on-duty of the switching element for booster circuit primary current choppering, which is determined by the above-described program control and determines the magnitude of the lap discharge current value at each time, is given by: When an expected overlapping discharge current is not obtained, a means for correcting the overlapping discharging current is also provided, so that more precise and accurate overlapping discharging can be performed.

On the other hand, according to the present invention, from another viewpoint, in the above-described lap discharge type ignition device, the timing at which the microcomputer should start the lap discharge can be determined without depending on the signal from the current interrupt circuit. Detecting and confirming that a discharge current has been generated by interrupting current on the secondary side of the ignition coil also provides a device that can be determined by confirming that the lap discharge circuit unit can be made into a single unit or a module.
Wiring work at the time of mounting on an actual vehicle is simplified, and the wiring system itself is also simplified. This effect becomes more remarkable as the number of cylinders of the vehicle mounted increases. Further, according to the device of the specific aspect of the present invention, even if the wiring connecting the secondary side of the ignition coil, which should generate the discharge current based on the current interruption, and the high-voltage output terminal of the booster circuit is disconnected, If the wiring is disconnected, the overlapping discharge circuit section itself does not operate in the first place, so that the danger of a high voltage appearing at the exposed high voltage output terminal can be avoided.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of an embodiment of a lap discharge type ignition device configured according to the present invention.

FIG. 2 is an explanatory diagram comparatively showing signal, voltage and current waveforms of main parts of the lap discharge type ignition device according to the present invention and a conventional example.

FIG. 3 is a view suitable for the apparatus of the embodiment of the present invention shown in FIG.
FIG. 9 is an explanatory diagram illustrating a specific example of program control according to the internal combustion engine speed with respect to the output time and on-duty of the switching element driving oscillation signal.

FIG. 4 is an explanatory diagram according to a specific example of a converted voltage waveform appearing at both ends of a discharge current detection resistor in the device of the embodiment of the present invention shown in FIG.

FIG. 5 is an explanatory diagram according to a specific example of a voltage waveform corresponding to a booster circuit output voltage in the device according to the embodiment of the present invention shown in FIG. 1;

FIG. 6 is a circuit configuration diagram of a typical example of a conventional overlap discharge type ignition device.

[Explanation of symbols]

10 Current cutoff circuit section, 11 Ignition timing sensor, 12 Ignition control circuit unit, 13 Current cutoff unit, 14 Ignition coil, 15 Spark plug, 17 wiring, 23 Boost transformer, 30 Overlap discharge circuit section, 31 Microcomputer, 32 Switching element Drive circuit, 33 booster circuit, 34 current detection circuit including discharge current generation detection circuit and current value detection circuit, 35 voltage detection circuit, Rd current detection resistor.

Claims (34)

(57) [Claims] 1. A cylinder which cuts off a primary current of an ignition coil every time a cylinder of an internal combustion engine reaches an ignition timing to generate a high voltage on a secondary side of the ignition coil, and outputs the high voltage to the cylinder which has reached the ignition timing. A current interrupting circuit section for supplying a discharge current which causes a discharge spark to be generated in the spark plug by breaking the discharge gap of the spark plug by applying the spark current to the spark plug provided in the spark plug, and a primary current of the step-up transformer by a switching element. Chopper is performed for a predetermined time at a frequency to generate a high voltage on the secondary side of the step-up transformer in accordance with the on-duty of the switching element, and an output current based on the high voltage is made the same as the discharge current. And a lap discharge circuit for obtaining a lap discharge current for sustaining the discharge spark generated in the ignition plug over the predetermined time by superimposing in a polarity. A discharge-type ignition device, wherein the value of the secondary-side high voltage of the booster circuit is increased to a value that prevents the discharge spark generated in the ignition plug from blowing out even when the rotation speed of the internal combustion engine is increased. The microcomputer performs program control on the relationship between the internal combustion engine rotation speed and the on-duty of the switching element, and variably sets the on-duty to an appropriate value according to the current internal combustion engine rotation speed. The microcomputer performs a basic control mode in which the microcomputer performs an overlap discharge current to be obtained at the on-duty set by the program control according to the internal combustion engine speed at each ignition time. A current value detecting means for detecting an actual magnitude of the overlap discharge current flowing over the predetermined time with respect to a reference current value being a value. When the circuit recognizes that the actually detected current value is lower, it creates and stores correction data relating to the set on-duty; the ignition time for the next and subsequent ignition times, and When the engine speed is the same or substantially the same as the internal combustion engine speed of the ignition device that produced the correction data, the microcomputer corrects the stored duty for the on-duty to be set by the program control. A new on-duty is set by adding a correction based on the data, and the switching element is operated in accordance with the new on-duty to control so as to increase the overlap discharge current value of the ignition cycle. Lap discharge type ignition device. 2. The lap discharge ignition device according to claim 1, wherein the microcomputer recognizes that the actually detected current value is higher than the reference current value. Generating and storing the correction data relating to the set on-duty; and storing the same or substantially the same internal combustion engine rotation speed as the ignition rotation for which the correction data was generated for the next and subsequent ignition turns. In the ignition cycle, the microcomputer sets a new on-duty by adding a correction based on the stored correction data to the on-duty to be set by the program control, and sets the new on-duty in accordance with the new on-duty. Controlling the overlap discharge current value of the ignition cycle to be lower by operating a switching element; apparatus. 3. Each cylinder of an internal combustion engine interrupts a primary current of an ignition coil every time an ignition timing is reached to generate a high voltage on a secondary side of the ignition coil, and the high voltage is applied to the cylinder which has reached the ignition timing. A current interrupting circuit section for supplying a discharge current which causes a discharge spark to be generated in the spark plug by breaking the discharge gap of the spark plug by applying the spark current to the spark plug provided in the spark plug, and a primary current of the step-up transformer by a switching element. Chopper is performed for a predetermined time at a frequency to generate a high voltage on the secondary side of the step-up transformer in accordance with the on-duty of the switching element, and an output current based on the high voltage is made the same as the discharge current. And a lap discharge circuit for obtaining a lap discharge current for sustaining the discharge spark generated in the spark plug over the predetermined time by superimposing in a polarity. A discharge-type ignition device, wherein the value of the secondary-side high voltage of the booster circuit is increased to a value that prevents the discharge spark generated in the ignition plug from blowing out even when the rotation speed of the internal combustion engine is increased. The microcomputer performs program control on the relationship between the internal combustion engine rotation speed and the on-duty of the switching element, and variably sets the on-duty to an appropriate value according to the current internal combustion engine rotation speed. The microcomputer performs a basic control mode in which the microcomputer performs an overlap discharge current to be obtained at the on-duty set by the program control according to the internal combustion engine speed at each ignition time. A current value detecting means for detecting an actual magnitude of the overlap discharge current flowing over the predetermined time with respect to a reference current value being a value. In accordance with a time rate at which the current value actually detected by the circuit is lower than the reference current value within the predetermined time, the correction data relating to the set on-duty is generated and stored; In the subsequent ignition turns, in which the internal combustion engine speed is the same as or substantially the same as the internal combustion engine speed of the ignition time for which the correction data was created, the microcomputer should be set by the program control. A new on-duty is set by adding a correction based on the stored correction data to the on-duty, and the switching element is operated in accordance with the new on-duty to increase the overlapping discharge current value of the ignition cycle. Lap discharge type ignition device characterized by the above-mentioned. 4. The lap discharge ignition device according to claim 3, wherein the microcomputer detects that the actually detected current value is higher than the reference current value within the predetermined time. The correction data relating to the set on-duty is generated and stored according to the time ratio that is set. The internal combustion engine rotation speed of the ignition time for which the correction data is generated for the next and subsequent ignition times. In the same or substantially the same ignition cycle as above, the microcomputer sets a new on-duty by adding a correction based on the stored correction data to the on-duty to be set by the program control. Controlling the switching element in accordance with an appropriate on-duty to control the overlap discharge current value of the ignition cycle to be low. Lap discharge type ignition device. 5. The lap discharge ignition device according to claim 1, wherein the microcomputer controls the switching element according to the new on-duty to increase the lap discharge current value. The reference current value is also slightly increased when performing the operation. 6. The lap discharge ignition device according to claim 2, wherein the microcomputer operates the switching element according to the new on-duty so as to reduce the lap discharge current value. When controlling,
The reference current value is also slightly changed to a lower value; 7. The lap discharge type ignition device according to claim 1, 2, 3, 4, 5, or 6, wherein the detection of the current by the current value detection circuit is performed in a path through which the lap discharge current flows. A lap discharge type ignition device characterized in that the voltage is converted into a voltage across a current detection resistor inserted in series; and the reference current value is also given by a corresponding voltage value in the microcomputer. 8. The method of claim 1, 2, 3, 4, 5, 6, or 7.
The microcomputer according to any one of the preceding claims, wherein the microcomputer is connected to the secondary side of the step-up transformer at the time of on-duty set by the program control according to the internal combustion engine speed at each ignition time. For the reference voltage value for the high voltage to be obtained,
When the voltage detection circuit that detects the actual value of the high voltage generated over the predetermined time on the secondary side of the step-up transformer recognizes that the actually detected voltage value is lower, Prepares and stores correction data relating to the set on-duty; and stores the same or substantially the same number of revolutions of the internal combustion engine as the ignition times for which the correction data was produced for the next and subsequent ignition times. At the same ignition time, the microcomputer sets a new on-duty by adding a correction based on the stored correction data to the on-duty to be set by the program control, and sets the new on-duty in accordance with the new on-duty. Controlling the step-up transformer to increase the secondary high voltage by operating a switching element; Location. 9. When each cylinder of the internal combustion engine reaches the ignition timing, the primary current of the ignition coil is cut off to generate a high voltage on the secondary side of the ignition coil, and the high voltage is applied to the cylinder that has reached the ignition timing. A current interrupting circuit section for supplying a spark current provided to the ignition plug to break a discharge gap of the spark plug and generate a discharge spark in the spark plug, and a primary current of the step-up transformer by a switching element. Chopper is performed for a predetermined time at a frequency, and a high voltage having a magnitude corresponding to the on-duty of the switching element is generated on the secondary side of the step-up transformer, and an output current based on the high voltage is made equal to the discharge current. And a lap discharge circuit for obtaining a lap discharge current for sustaining the discharge spark generated in the ignition plug over the predetermined time by superimposing in a polarity. A discharge-type ignition device, wherein the value of the secondary-side high voltage of the booster circuit is increased to a value that prevents the discharge spark generated in the ignition plug from blowing out even when the rotation speed of the internal combustion engine is increased. The microcomputer performs program control on the relationship between the internal combustion engine speed and the on-duty of the switching element, and variably sets the on-duty to an appropriate value according to the current internal combustion engine speed. The microcomputer controls the secondary of the step-up transformer at the time of on-duty set by the program control according to the internal combustion engine speed at each ignition time. For the reference voltage value for the high voltage to be obtained on the side,
When the voltage detection circuit that detects the actual value of the high voltage generated over the predetermined time on the secondary side of the step-up transformer recognizes that the actually detected voltage value is lower, Prepares and stores correction data relating to the set on-duty; and stores the same or substantially the same number of revolutions of the internal combustion engine as the ignition times for which the correction data was produced for the next and subsequent ignition times. At the same ignition time, the microcomputer sets a new on-duty by adding a correction based on the stored correction data to the on-duty to be set by the program control, and sets the new on-duty in accordance with the new on-duty. Controlling the step-up transformer to increase the secondary high voltage by operating a switching element; Location. 10. The lap discharge ignition device according to claim 8, wherein the microcomputer recognizes that the actually detected voltage value is higher than the reference voltage value. The correction data relating to the set on-duty is generated and stored. Whether the internal combustion engine rotational speed of the next ignition cycle is the same as the internal combustion engine rotational speed of the ignition cycle for which the correction data is generated is stored. At substantially the same ignition time, the microcomputer sets a new on-duty by adding a correction based on the stored correction data to the on-duty to be set by the program control, and sets the new on-duty according to the new on-duty. Controlling the value of the high voltage on the secondary side of the step-up transformer by operating the switching element; Ne discharge type ignition device. 11. The lap discharge type ignition device according to claim 1, wherein the microcomputer is configured to determine the number of revolutions of the internal combustion engine at each ignition time. In response to the reference voltage value relating to the high voltage to be obtained on the secondary side of the step-up transformer at the time of the on-duty set by the program control,
The voltage value actually detected by the voltage detecting circuit for detecting the actual value of the high voltage generated on the secondary side of the step-up transformer over the predetermined time becomes lower within the predetermined time. The correction data relating to the set on-duty is generated and stored in accordance with the time rate set, and the rotation speed of the internal combustion engine is the ignition time after the next time, and the rotation speed of the internal combustion engine is the rotation time for which the correction data is generated. At the same or almost the same number of ignition times, the microcomputer sets a new on-duty by adding a correction based on the stored correction data to the on-duty to be set by the program control. Controlling the switching element in accordance with an appropriate on-duty to increase the value of the secondary high voltage of the step-up transformer; Discharge type ignition device. 12. Each time the cylinder of the internal combustion engine reaches the ignition timing, the primary current of the ignition coil is interrupted to generate a high voltage on the secondary side of the ignition coil, and the high voltage is applied to the cylinder which has reached the ignition timing. A current interrupting circuit section for supplying a discharge current which causes a discharge spark to be generated in the spark plug by breaking the discharge gap of the spark plug by applying the spark current to the spark plug provided in the spark plug, and a primary current of the step-up transformer by a switching element. Chopper is performed for a predetermined time at a frequency to generate a high voltage on the secondary side of the step-up transformer in accordance with the on-duty of the switching element, and an output current based on the high voltage is made the same as the discharge current. And a lap discharge circuit section for obtaining a lap discharge current for maintaining the discharge spark generated in the ignition plug over the predetermined time by superimposing in polarity. A lap discharge type ignition device, wherein the value of the secondary high voltage of the booster circuit is increased to a value that prevents the discharge spark generated in the ignition plug from being blown out even when the rotation speed of the internal combustion engine is increased. The microcomputer performs program control on the relationship between the internal combustion engine rotation speed and the on-duty of the switching element, and variably sets the on-duty to an appropriate value according to the current internal combustion engine rotation speed. The microcomputer controls the secondary of the step-up transformer at the on-duty set by the program control according to the internal combustion engine speed at each ignition time. For the reference voltage value related to the high voltage to be obtained on the side,
The voltage value actually detected by the voltage detecting circuit for detecting the actual value of the high voltage generated on the secondary side of the step-up transformer over the predetermined time becomes lower within the predetermined time. The correction data relating to the set on-duty is generated and stored in accordance with the time rate set, and the rotation speed of the internal combustion engine is the ignition time after the next time, and the rotation speed of the internal combustion engine is the rotation time for which the correction data is generated. At the same or almost the same number of ignition times, the microcomputer sets a new on-duty by adding a correction based on the stored correction data to the on-duty to be set by the program control. Controlling the switching element in accordance with an appropriate on-duty to increase the value of the secondary high voltage of the step-up transformer; Discharge type ignition device. 13. The lap discharge ignition device according to claim 11, wherein the microcomputer detects that the actually detected voltage value is higher than the reference voltage value within the predetermined time. The correction data relating to the set on-duty is generated and stored in accordance with the time rate that has been set; and the internal combustion engine of the ignition time that is the ignition time of the next and subsequent ignition times and in which the correction data is generated At the same or almost the same number of revolutions as the number of revolutions, the microcomputer sets a new on-duty by adding a correction based on the stored correction data to the on-duty to be set by the program control. Controlling the step-up transformer secondary-side high voltage to decrease by operating the switching element according to the new on-duty; Overlapping discharge ignition system according to claim. 14. The lap discharge type ignition device according to claim 8, 9, 11, or 12, wherein the microcomputer sets the new on-duty and sets the value of the secondary high voltage of the step-up transformer. The above-mentioned reference voltage value is also changed to a slightly higher value when performing control to increase the value. 15. The lap discharge type ignition device according to claim 10, wherein the microcomputer sets the new on-duty and controls so as to reduce the value of the secondary high voltage of the step-up transformer. The above-mentioned reference voltage value is also slightly changed to a lower value when performing the operation. 16. The lap discharge type ignition device according to claim 8, 9, 10, 11, 12, 13, 14, or 15, wherein the reference voltage value and the voltage actually detected by the voltage detection circuit. The comparison with the value is performed by each other with a value obtained by dividing each of them by an equal predetermined magnification. 17. The method of claim 1, 2, 3, 4, 5, 6, 7,
18. The lap ignition type ignition device according to 8, 9, 10, 11, 12, 13, 14, 15, or 16, wherein the microcomputer is configured to determine the number of revolutions of the internal combustion engine and the predetermined time for operating the switching element. A program is also performed on the relationship, and the predetermined time is variably set so as to have an appropriate time value according to the internal combustion engine speed at each time. 18. The method of claim 1, 2, 3, 4, 5, 6, 7,
The lap discharge type ignition device according to 8, 9, 10, 11, 12, 13, 14, 15, 16, or 17, wherein when the discharge current flows due to the current interruption, the discharge current is detected. The microcomputer has a discharge current generation detection circuit that outputs a generation detection signal; the microcomputer receives the discharge current generation detection signal, and generates an oscillation signal according to the on-duty set at the time from when the generation of the discharge current is confirmed. Wherein the switching element performs an on / off operation directly by the oscillation signal or an on / off operation by the oscillation signal via a drive circuit. 19. The lap discharge type ignition device according to claim 18, wherein the microcomputer receives the discharge current generation detection signal and calculates the respective internal combustion engine speed according to the generation interval of the signal. A lap discharge type ignition device characterized by the above-mentioned. 20. The lap discharge type ignition device according to claim 19, wherein the discharge current generation detection circuit has a current detection resistor inserted in series in a discharge path of the discharge current. The discharge current generation detection signal output from the generation detection circuit is represented by a voltage value signal appearing at both ends of the current detection resistor. The microcomputer detects that the voltage value signal has exceeded a predetermined value. And confirming the generation of the discharge current. 21. The lap discharge type ignition device according to claim 20, wherein the current detection resistor provided in the discharge current generation detection circuit is the same as the current detection resistor provided in the current value detection circuit. An overlap discharge type ignition device characterized by the following. 22. The lap discharge ignition device according to claim 21, wherein the discharge current generation detection circuit has a buffer amplifier for passing a voltage across the current detection resistor; and the output of the buffer amplifier is the microcomputer. And a current value detection circuit. 23. The lap discharge type ignition device according to claim 22, wherein the current value detection circuit includes a voltage value corresponding to the reference current value provided from the microcomputer and a voltage of the output of the buffer amplifier. The microcomputer outputs a binary signal that inverts the high and low levels according to the magnitude relationship between the voltage values; Determining whether the current value actually detected at each time is higher or lower than the reference current value. 24. The lap discharge type ignition device according to claim 21, 22 or 23, wherein one end of the secondary side of the ignition coil is connected to one end of a discharge gap of the ignition plug, and one end of the current detection resistor. Are electrically connected to the other end of the discharge gap of the spark plug via ground, respectively; the lap discharge circuit is configured as a single unit, and is electrically connected to the current cutoff circuit. Is only a connection line between the other end of the secondary side of the ignition coil in the current cutoff circuit section and the other end of the current detection resistor in the overlap discharge circuit section. Ignition device. 25. The overlap discharge type ignition device according to claim 24, wherein the current cutoff circuit section and the overlap discharge circuit section are provided one by one in relation to each cylinder of the internal combustion engine. A lap discharge type ignition device characterized by the following. 26. The lap discharge ignition device according to claim 25, wherein the current interruption circuit section and the lap discharge circuit section are provided one by one in relation to each cylinder of the internal combustion engine. However, only the microcomputer in each of the lap discharge circuits is common to all lap discharge circuits. 27. The lap discharge ignition device according to claim 26, wherein the common microcomputer has a dedicated input for receiving an output of the discharge current generation detection circuit in each of the lap discharge circuits. Specifying which lap discharge circuit section to which the discharge current generation detection circuit that has issued the discharge current generation detection signal belongs, based on which input is supplied with the discharge current generation detection signal. A lap discharge type ignition device characterized by the following. 28. The lap discharge ignition apparatus according to claim 27, wherein the common microcomputer selectively receives an output of the discharge current generation detection circuit in each of the lap discharge circuits. The microcomputer sequentially switches the discharge current detection signal input switching means in a known order, and when the microcomputer receives the discharge current generation detection signal via the input means, the microcomputer switches the discharge current detection signal input switching means to the known order. A lap discharge circuit section to which the discharge current generation detection circuit that has generated the discharge current generation detection signal belongs, based on the following. 29. The lap discharge ignition device according to claim 27 or 28, wherein the common microcomputer has a dedicated input for receiving an output of the current value detection circuit in each of the lap discharge circuits. Having an overlapping discharge type ignition device. 30. The overlap discharge type ignition device according to claim 27 or 28, wherein the common microcomputer selectively receives an output of the current value detection circuit in each of the overlap discharge circuit units. The microcomputer has a detection signal input switching unit; and the microcomputer controls the switching of the current value detection signal input switching unit so as to receive an output from the current value detection circuit in the specified overlap discharge circuit unit. A lap discharge type ignition device characterized by the following. 31. The lap discharge type ignition device according to claim 27, 28, 29 or 30, wherein the common microcomputer is dedicated to receiving an output of the voltage detection circuit in each of the lap discharge circuits. Igniter having the following inputs: 32. The overlap discharge type ignition device according to claim 27, 28, 29 or 30, wherein the common microcomputer selectively outputs an output of the voltage detection circuit in each of the overlap discharge circuit units. The microcomputer has a voltage detection signal input switching means for receiving; the microcomputer switches and controls the voltage detection signal input switching means so as to receive an output from the voltage detection circuit in the specified overlapping discharge circuit unit; An overlap discharge type ignition device characterized by the above-mentioned. 33. Claim 26, 27, 28, 29, 30, 31 or
33. The lap discharge ignition apparatus according to claim 32, wherein the common microcomputer outputs the signal indicating the on-duty set at each time for driving each of the switching elements in each of the lap discharge circuits. A lap discharge type ignition device having a dedicated output for outputting to each switching element. 34. Claim 26, 27, 28, 29, 30, 31 or
33. The lap discharge ignition apparatus according to claim 32, wherein the common microcomputer sends the signal representing the on-duty set at each time to the switching element associated with the cylinder at which the ignition timing has reached at that time. An output signal switching unit for selectively outputting; when the microcomputer receives a discharge current generation detection signal from the current generation detection circuit in any one of the overlap discharge circuit units, the microcomputer generates the signal. Controlling the output signal switching means so as to output the signal indicating the on-duty to the switching element in the lap discharge circuit section having the discharge current generation detection circuit;