JP2013113122A - Overlapping discharge-type ignition device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge-type ignition device for an internal combustion engine, capable of being installed in a narrow mounting space with the size of the device being reduced at low cost, and controlling discharge time or discharge energy in a suitable manner for the internal combustion engine.SOLUTION: An overlapping discharge function to be added to the ignition device for internal combustion engine which applies discharge current by producing a discharge breakdown in a discharge gap g of an ignition plug 2 by an ignition coil 1 that is operated based on an ignition signal is configured such that a DC high voltage obtained by operating a DC-AC booster circuit 3 by an overlap time control circuit 6 to supply alternating current for generating an overlapping voltage to a multistage voltage-doubling rectifier circuit 4 is overlapped with the induction voltage of a secondary coil 1b at the same polarity. The overlap time control circuit 6 changes the operation time of the DC-AC booster circuit 3 to optionally control the overlap time, and the DC-AC booster circuit changes the voltage to be supplied to the multistage voltage-doubling rectifier circuit 4 to control the DC voltage value obtained from the multistage voltage-doubling rectifier circuit 4.

Description

  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 ignition device for a multiple discharge internal combustion engine.

  Recently, lean burn engines and high EGR engines have been adopted as internal combustion engines mounted on vehicles to improve fuel efficiency, but these engines are not very efficient in ignition. I need it. In view of this, an ignition device for a multi-discharge internal combustion engine that superimposes the high-voltage output of the DC-DC converter on the secondary output of the ignition coil generated by the classic current interruption principle has been proposed (for example, patent document). 1).

  In such a conventional igniter for a multi-discharge internal combustion engine, by interrupting the primary current of the ignition coil, a high voltage of several kV generated on the secondary side of the ignition coil causes discharge breakdown in the discharge gap of the spark plug. Waking up and starting to flow a discharge current from the secondary side of the ignition coil, while maintaining a DC voltage (usually, about 500 V or more) higher than the discharge sustaining voltage value capable of maintaining the discharge state by a separately provided booster circuit, The output current from the booster circuit is additionally superimposed on the ignition coil discharge current. In fact, according to such an ignition device for a multi-discharge internal combustion engine, a large discharge energy can be obtained in the spark plug for a relatively long time, so that the ignitability to the fuel is improved and the fuel consumption is also improved.

JP-A-8-68372

  However, in the ignition device for the overlap discharge type internal combustion engine described in Patent Document 1 above, the high voltage output of the DC-DC converter, particularly the booster, is superimposed on the secondary output of the ignition coil to superimpose the high voltage output of the DC-DC converter. It is necessary to select high voltage components for the transformer and the charge / discharge capacitor, and it is difficult to reduce the size of the DC-DC converter. For this reason, the DC-DC converter cannot be installed around the ignition coil, and the overlapping discharge function unit including the DC-DC converter must be installed at a site away from the ignition coil. In order to lead out the high voltage output to the ignition coil 2, high withstand voltage wiring is required. Therefore, the conventional ignition device for a multi-discharge internal combustion engine has problems in terms of cost and storage space.

  In lean burn engines, high EGR, etc., there are cases where short discharge is desirable and long discharge is desirable even with the same high energy depending on the state of the air-fuel mixture. Although there is a need for an ignition device for a multi-discharge internal combustion engine that can be performed, in the conventional multi-discharge internal combustion engine ignition device, the overlap time and overlap current are determined by the capacity of the charge / discharge capacitor. It is difficult to arbitrarily change the current. Moreover, the conventional overlap discharge type internal combustion engine ignition device retains the design overlap time and overlap current, and as a result, excessive discharge energy is supplied and unnecessary power consumption continues or ignition occurs. There is also a problem that the consumption of the plug electrode is accelerated.

  Therefore, the present invention is capable of downsizing the apparatus at low cost, can be installed in a small in-vehicle space, and can be used for a discharge type internal combustion engine that can be diverted to a structure capable of controlling discharge time and discharge energy suitable for the internal combustion engine. An object is to provide an ignition device.

  In order to solve the above-described problem, the invention according to claim 1 is configured to block the current of the primary coil of the ignition coil in response to the ignition signal, induce a high voltage in the secondary coil, and have the same polarity as the high voltage. In an ignition device for a multi-discharge internal combustion engine that superimposes a voltage, causes a spark discharge in a discharge gap of an ignition plug, and ignites an air-fuel mixture in a combustion chamber, at the timing of high voltage induction of a secondary coil based on the ignition signal A superimposed voltage generating operation control means for outputting a superimposed voltage generating alternating current of a required voltage / required frequency, and a voltage doubler rectifier circuit operating within a cycle of the superimposed voltage generating alternating current supplied from the superimposed voltage generating operation control means. A multi-stage voltage doubler rectifier that combines multiple stages and outputs a DC high voltage that is several times the peak value of the input peak value, and outputs the DC high voltage output from the multi-stage voltage doubler rectifier. Superimposing a high voltage of the same polarity induced in Le of the secondary coil, characterized in that so as to perform overlapping discharge by applying to the spark plug.

  According to a second aspect of the present invention, in the ignition device for an overlapped discharge internal combustion engine according to the first aspect, by changing the voltage value of the superimposed voltage generating AC output from the superimposed voltage generating operation control means. The voltage output from the multi-stage voltage doubler rectifier can be adjusted.

  According to a third aspect of the present invention, there is provided an overlap time control means capable of arbitrarily controlling the driving time of the superimposed voltage generation operation control means in the ignition device for the supercharging type internal combustion engine according to the first or second aspect. And the superposition time of the DC high voltage generated by the multi-stage voltage doubler rectifier can be arbitrarily changed.

  According to a fourth aspect of the present invention, in the ignition device for a multiple discharge internal combustion engine according to any one of the first to third aspects, the multistage voltage doubler rectifier is the same as the ignition coil. It is characterized by being housed in a case.

  According to the first aspect of the present invention, the superimposed voltage generating operation control means for outputting the superimposed voltage generating alternating current of the required voltage / required frequency at the timing of the high voltage induction of the secondary coil based on the ignition signal, and the superimposing Multi-stage voltage doubler that combines multiple voltage rectifier circuits that operate within the period of the superimposed voltage generation AC supplied from the voltage generation operation control means, and outputs a DC high voltage that is the number of stages of the input peak value. Rectifying means, and the DC high voltage output from the multi-stage voltage doubler rectifying means is superimposed with the same polarity as the high voltage induced in the secondary coil of the ignition coil, and applied to the spark plug for overlap discharge Therefore, the withstand voltage of the diode and capacitor used in each voltage doubler rectifier circuit constituting the multistage voltage doubler rectifier is sufficient to be about twice that of the superimposed voltage generating AC output. Because it is not necessary that a large capacity such as charging and discharging capacitor of a conventional lap discharge type ignition device for an internal combustion engine, enables miniaturization of cost containment and components, it can be installed to reasonably narrow automotive space.

  According to the invention of claim 2, the voltage output from the multi-stage voltage doubler rectifier can be adjusted by changing the voltage value of the superimposed voltage generating AC output from the superimposed voltage generating operation control unit. Since it did in this way, the discharge current which can perform the discharge of the characteristic suitable for the state of air-fuel mixture can be sent.

  According to the third aspect of the present invention, the superposition time control means capable of arbitrarily controlling the driving time of the superposition voltage generation operation control means is provided, and the superposition time of the DC high voltage generated by the multistage voltage doubler rectification means. Since the discharge current can be arbitrarily changed, the discharge current can be continued for an overlap time that allows discharge having characteristics suitable for the state of the air-fuel mixture.

  In addition, according to the invention adopting the configurations of claim 2 and claim 3 together, since the overlap time and the overlap current can be arbitrarily changed, the optimum discharge time and the optimum discharge energy are supplied to the state of the air-fuel mixture. In addition, it is possible to avoid problems such as wasteful power consumption due to excessive discharge energy being supplied and rapid consumption of the spark plug electrode.

  According to the invention of claim 4, since the multistage voltage doubler rectifier is housed in the same case as the ignition coil, a high voltage supply line from the multistage voltage doubler rectifier to the ignition coil. Can be accommodated in the case, and it is not necessary to route the DC high-voltage line, and it is not necessary to secure a high-breakdown-voltage wiring material and wiring space.

1 is a schematic configuration diagram of an ignition device for a multi-discharge internal combustion engine shown as an embodiment of the present invention. FIG. 2 is an operation waveform diagram at the time of ignition in the ignition device for the multiple discharge internal combustion engine of FIG. 1.

  Next, an embodiment of an ignition device for a multiple discharge internal combustion engine according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a schematic configuration of an embodiment in which an ignition device for a multiple discharge type internal combustion engine according to the present invention is applied to an engine ignition device for a vehicle. An ignition coil 1 (for example, a primary coil 1a, a secondary coil 1b) is shown. , The iron core 1c and the switching element 1d) cause a spark discharge in the discharge gap g of the spark plug 2, and ignites the air-fuel mixture in the combustion chamber of the vehicle engine (not shown).

  For example, when the switching element 1d of the ignition coil 1 is turned on by an ignition signal from the engine control unit (ECU), a current flows to the primary coil 1a to which the DC voltage VB is supplied from a vehicle battery (not shown). Thereafter, the switching element 1d is turned off at the falling edge of the ignition signal, the current of the primary coil 1a is cut off, and a spark discharge is caused in the gap g between the discharges of the spark plug 2 by the high voltage induced in the secondary coil 1b. .

  Therefore, in the ignition apparatus for a multi-discharge internal combustion engine according to this embodiment, in order to generate a voltage to be superimposed on the high voltage induced in the secondary coil 1b, the “high voltage of the secondary coil based on the ignition signal” is generated. The superimposed voltage generation AC (for example, AC 200 V) is generated from the DC-AC booster circuit 3 as the superimposed voltage generation operation control means for outputting the superimposed voltage generation AC of the required voltage and required frequency at the induction timing. Multi-stage voltage doubler rectifier means that combines multiple voltage doubler rectifier circuits that operate within the cycle of the superimposed voltage generation AC supplied from the operation control means, and outputs a DC high voltage that is the number of stages of the input peak value. Is supplied to the multi-stage voltage doubler rectifier circuit 4 and a DC high voltage (for example, DC 1.2 kV) is output from the multi-stage voltage doubler rectifier circuit 4, and this DC high voltage is induced in the secondary coil 1b. By superimposing the pressure is to adjust the size and the discharge time of the discharge current that causes the ignition plug 2. A high voltage diode 5 is provided between the secondary coil 1b and the ground point so that the secondary coil 1b side is an anode and the ground side is a cathode, and the DC high voltage output from the multistage voltage doubler rectifier circuit 4 is provided. By connecting the positive side to the cathode side of the high-voltage diode 5 and the negative side to the anode side of the high-voltage diode 5, the high voltage induced in the secondary coil 1 b is superimposed with the same polarity.

  The DC-AC booster circuit 3 starts operating at the timing when the switching element 1d of the ignition coil 1 is turned off by the ignition signal (for example, the detection timing of the pulse falling of the ignition signal), and after a predetermined overlap time has elapsed, Although the operation may be stopped by, for example, “the overlap time control means that can arbitrarily control the drive time of the overlap voltage generation operation control means so that the overlap time according to the combustion characteristics of the internal combustion engine can be easily adjusted. The superposition time control circuit 6 is provided, and the superposition time (time for outputting the superposition voltage generation AC from the DC-AC booster circuit 3) can be arbitrarily changed by setting the superposition time control circuit 6. I made it.

  Here, the operation of each part of the ignition device for the multi-discharge internal combustion engine according to the present embodiment will be described with reference to the operation waveform of FIG.

  First, when a pulse having a predetermined width is input to the ignition coil 1 as an ignition signal, the switching element 1d is turned on by the rising edge of the pulse, and the primary current starts to flow through the primary coil 1a, but the switching element 1d is started by the falling edge of the ignition signal. When is turned off, no current flows through the primary coil 1a, so that a large secondary voltage is instantaneously induced in the secondary coil 1b of the ignition coil 1.

  As described above, the overlap time control signal output from the overlap time control circuit 6 to the DC-AC booster circuit 3 is turned ON at the timing when the secondary voltage is induced in the secondary coil 1b (timing of the pulse fall of the ignition signal). (For example, the signal level is changed from L to H), and output of the superimposed voltage generation AC by the DC-AC booster circuit 3 is started. The DC-AC booster circuit 3 continues to output the superimposed voltage generation AC until the overlap time control signal from the overlap time control circuit 6 is turned off (the signal level changes from H to L). A high DC voltage is output from the voltage doubler rectifier circuit 4.

  The DC-AC booster circuit 3 is exemplified by a DC voltage VB (for example, DC12V) of the on-vehicle battery that is output with an AC voltage of 200V. However, the DC-AC booster circuit 3 is not limited to this and is not limited to this. May be set arbitrarily. Alternatively, the DC-AC booster circuit 3 may be provided with a function that can adjust the output voltage value. Further, the voltage value output from the multistage voltage doubler rectifier circuit 4 is adjusted by changing the ON duty time of the superimposed voltage generating alternating current (rectangular wave) generated by the DC-AC booster circuit 3 using PWM control. You may do it.

  The multistage voltage doubler rectifier circuit 4 that receives the superimposed voltage generating alternating current from the DC-AC booster circuit 3 configured as described above is a voltage doubler rectifier circuit that outputs a direct current voltage that is twice the peak value of the input alternating current. , And a DC high voltage of 1.2 kV DC, which is 6 times higher than the AC 200 V input, can be obtained.

  The voltage doubler rectifier circuit used for the multistage voltage doubler rectifier circuit 4 may be a known one. In the three-stage voltage doubler rectifier circuit shown in FIG. 1, the capacitor C1 is charged by the diode D1, and the capacitor C2 is charged by the diode D2. Similarly, as a result of charging the capacitor C3, the capacitor C4, the capacitor C5, and the capacitor C6 by the diode D3, the diode D4, the diode D5, and the diode D6, the capacitor C2, the capacitor C4, and the capacitor C6 connected in series are Since each is charged approximately twice the input peak value, a 6-fold direct current can be obtained. When the ON duty time of the superimposed voltage generating AC (rectangular wave) is changed using PWM control, the peak value of the rectangular wave input to the multistage voltage doubler rectifier circuit 4 does not change, but the ON / OFF duty is changed. Since the charging voltage of each of the capacitors C1 to C6 decreases according to the ratio, the DC voltage (capacitor charging voltage × 2 × stage number) obtained from the multistage voltage doubler rectifier circuit 4 can be adjusted.

  That is, when a DC high voltage is acquired using the multistage voltage doubler rectifier circuit 4 as shown in FIG. 1, the withstand voltages of the diodes D1 to D6 and the capacitors C1 to C6 of each voltage doubler rectifier circuit are all for generating a superimposed voltage. Since there is no problem if it is twice or more the AC voltage value, there is no need for a large capacity like the charge / discharge capacitor of the conventional ignition device for a multi-discharge internal combustion engine, and it is possible to reduce the size and cost of parts. Note that the multistage voltage doubler rectifier circuit 4 is not limited to three stages, and may be two stages or four stages or more.

  The DC high voltage of 1.2 kV obtained from the multistage voltage doubler rectifier circuit 4 as described above continues until the overlap time control signal of the overlap time control circuit 6 is turned off (the signal level changes from H to L). Is output. However, when the DC high voltage obtained from the multi-stage voltage doubler rectifier circuit 4 is superimposed on the high voltage induced in the secondary coil 1b, it must be superimposed with the same polarity as the high voltage induced in the secondary coil 1b. Therefore, the superimposed voltage on the discharge electrode becomes an inverted waveform of the output of the multistage voltage doubler rectifier circuit.

  As described above, in the ignition device for a multi-discharge internal combustion engine according to the present embodiment, the DC high voltage output from the multistage voltage doubler rectifier circuit 4 is the same as the high voltage induced in the secondary coil 1b of the ignition coil 1. As shown in FIG. 2, the discharge waveform of the spark plug 2 is superimposed with the DC high voltage from the multi-stage voltage doubler rectifier circuit 4 even after a large current at the beginning of ignition flows, as shown in FIG. Thus, the spark plug 2 continues to be discharged until the overlap time controlled by the overlap time control circuit 6 elapses.

  In addition, in the ignition apparatus for the overlap discharge type internal combustion engine according to the present embodiment, the DC-AC booster circuit 3 that outputs the superimposed voltage generating alternating current, and the multistage that receives the superimposed voltage generating alternating current and generates a direct high voltage. Since the voltage doubler rectifier circuit 4 is used, the voltage value of the superimposed voltage generation AC output from the DC-AC booster circuit 3 serving as the superimposed voltage generation operation control means is increased or decreased. The voltage output from the multi-stage voltage doubler rectifier circuit 4 as the multi-stage voltage doubler rectifier can be adjusted to be higher or lower, so that a discharge current capable of discharging with characteristics suitable for the state of the air-fuel mixture can flow. it can.

  Further, since the driving time of the DC-AC booster circuit 3 as the superimposed voltage generation operation control means can be arbitrarily controlled by the overlap time control circuit 6 as the overlap time control means, the direct current generated by the multi-stage voltage doubler rectifier circuit 4 can be controlled. The stacking time of the high voltage can be lengthened, shortened, or arbitrarily changed, and the discharge current can be continued for a stacking time that allows discharge having characteristics suitable for the state of the air-fuel mixture.

  In addition, if the discharge energy adjustment function by the DC-AC booster circuit 3 and the overlap time adjustment function by the overlap time control circuit 6 are used together, the discharge energy superimposed on the overlap time can be arbitrarily changed. Thus, it is possible to supply the optimal discharge time and optimal discharge energy for the above-mentioned state, and it is possible to avoid the problem that unnecessary discharge of electric power continues due to excessive supply of the discharge energy or the consumption of the electrode of the spark plug 2 is accelerated.

  Further, since the multistage voltage doubler rectifier circuit 4 can be configured with small components, it can be easily housed in the same case as the ignition coil 1. Moreover, if the multistage voltage doubler rectifier circuit 4 and the high voltage diode 5 are housed in the same case as the ignition coil 1, the high voltage supply line from the multistage voltage doubler rectifier circuit 4 can be housed in the case, and the direct current There is no need to route a high voltage line, and it is not necessary to secure a wiring material or wiring space with a high breakdown voltage.

  As mentioned above, although the embodiment of the ignition device for the overlap discharge type internal combustion engine according to the present invention has been described based on the accompanying drawings, the present invention is not limited to this embodiment, and the configuration described in the claims. As long as the above is not changed, it may be carried out by diverting known equivalent technical means.

DESCRIPTION OF SYMBOLS 1 Ignition coil 1a Primary coil 1b Secondary coil 1c Iron core 1d Switching element 2 Spark plug g Discharge gap 3 DC-AC booster circuit 4 Multistage voltage doubler rectifier circuit 5 High voltage diode 6 Overlap time control circuit

Claims (4)

In response to the ignition signal, the current of the primary coil of the ignition coil is cut off, a high voltage is induced in the secondary coil, a voltage having the same polarity as the high voltage is superimposed, and a spark discharge is generated in the discharge gap of the spark plug. In an ignition device for a multi-discharge internal combustion engine that ignites an air-fuel mixture in a combustion chamber,
Superimposed voltage generation operation control means for outputting a superimposed voltage generation alternating current of a required voltage and a required frequency at the timing of high voltage induction of the secondary coil based on the ignition signal;
A multi-stage voltage rectifier circuit that operates within the period of the superimposed voltage generation AC supplied from the superimposed voltage generation operation control means is combined in multiple stages, and a multi-stage that outputs a DC high voltage that is multiple times the input peak value. Voltage rectifying means;
With
The DC high voltage output from the multi-stage voltage doubler rectifier is superimposed with the same polarity as the high voltage induced in the secondary coil of the ignition coil and applied to the spark plug to cause overlap discharge. An ignition device for a multi-discharge internal combustion engine characterized by the above.   2. The voltage output from the multistage voltage doubler rectifier can be adjusted by changing the voltage value of the superimposed voltage generating AC output from the superimposed voltage generating operation control unit. The ignition device for a multiple discharge internal combustion engine as described.   It is provided with an overlap time control means that can arbitrarily control the driving time of the superimposed voltage generation operation control means, and the overlap time of the DC high voltage generated by the multi-stage voltage doubler rectifier can be arbitrarily changed. The ignition device for a multi-discharge internal combustion engine according to claim 1 or 2.   The ignition device for a multi-discharge internal combustion engine according to any one of claims 1 to 3, wherein the multistage voltage doubler rectifier is housed in the same case as the ignition coil. .

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