JP2011174471A - Ignition device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain an ignition device for an internal combustion engine capable of stably feeding designated output current and always maintaining a good combustion state of the internal combustion engine even when voltage of a power source connected with an energy storage coil is fluctuated. <P>SOLUTION: The ignition device for an internal combustion engine performs repetitive on-off control of a second switching means S2 in order to apply current inverted to positive and negative sides to an ignition plug 6, and performs control having a period of rapidly increasing energy accumulated in the energy storage coil 3 by turning on a first switching means S1 and a period of slowly increasing energy accumulated in the energy storage coil 3 by turning off the first switching means S1 and turning on a fourth switching means S4 during a turning-off period of a second switching means S2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ignition device for an internal combustion engine, and more particularly to an ignition device for an internal combustion engine that increases ignition energy by repeatedly applying a pulse current whose polarity is reversed.

  In a spark ignition type internal combustion engine, an ignition discharge is generated in an ignition plug by an ignition device including an ignition coil, and the fuel introduced into the combustion chamber by the ignition discharge is used for combustion. In order to improve the combustion state of the internal combustion engine, a multiple discharge ignition device has been proposed in which ignition discharge is generated in the spark plug a plurality of times within one combustion stroke.

  For example, an energy storage coil connected in series to a DC voltage source and first switch means connected in series to the energy storage coil, and the energy storage coil and second switch means on the primary coil of the ignition coil, And an ignition plug is connected to the secondary coil of the ignition coil to constitute an ignition device. Then, by alternately turning on and off the first and second switch means, the energy storage coil is repeatedly charged and discharged, and the positive and negative polarities of the secondary coil of the ignition coil are reversed by the charge and discharge. There has been proposed an ignition control device for an internal combustion engine in which multiple discharges are performed by repeatedly flowing current (see, for example, Patent Document 1).

JP 2007-211631 A (column of claims, FIG. 1)

  However, in the ignition device for an internal combustion engine proposed in Patent Document 1, a desired current cannot be stably supplied to the spark plug depending on the voltage of a DC voltage source connected in series with the energy storage coil. There is a problem that the spark plug is worn or the ignition operation becomes unstable.

  The present invention has been made to solve such a problem, and even when the voltage of a power supply connected to the energy storage coil fluctuates, a predetermined output current can be stably supplied, and the internal combustion engine It is an object of the present invention to obtain an ignition device for an internal combustion engine that can always maintain a good combustion state.

  An ignition device for an internal combustion engine according to the present invention includes an energy storage coil having one end connected to a power source, first switch means connected to a lead wire halfway through the energy storage coil, and the other end of the energy storage coil. An ignition coil having one end of the primary winding connected through a diode and an ignition plug connected to the secondary winding, and a second switch means connected to the other end of the primary winding of the ignition coil And a fourth switch means connected to the other end of the energy storage coil, a first switch means, a second switch means, and a control means for controlling the fourth switch means. And the control means performs control for repeatedly turning on and off the second switch means in order to give a positive and negative current to the spark plug, and turning off the second switch means. In the meantime, a period in which the energy stored in the energy storage coil is suddenly increased by turning on the first switch means, the first switch means is turned off, and the fourth switch means is turned on. And a period during which the energy stored in the energy storage coil is gradually increased by being turned on.

  According to the ignition device for an internal combustion engine according to the present invention, even when the voltage of the power source connected to the energy storage coil fluctuates, a predetermined output current can be flowed stably, and wear of the spark plug can be accelerated. The combustion state of the internal combustion engine can always be kept good without consuming excess energy.

It is a figure which shows the structure of the ignition device of the internal combustion engine which concerns on Embodiment 1 of this invention. It is a figure which shows the circuit which keeps an energy storage coil current around the predetermined target value by making a coil current recirculate | reflux in the ignition device of the internal combustion engine which concerns on Embodiment 1 of this invention. 5 is a timing chart for explaining an operation of maintaining the energy storage coil current around a predetermined target value by causing the coil current to recirculate in the ignition device for an internal combustion engine according to Embodiment 1 of the present invention. 2 is a timing chart showing an overall operation sequence in the ignition device for an internal combustion engine according to the first embodiment of the present invention. It is a timing chart explaining operation | movement in case the input voltage is high in the conventional multi-ignition system. It is a timing chart explaining operation | movement in case the input voltage is low in the conventional multi-ignition system. It is a figure which shows the structure of the ignition device of the internal combustion engine which concerns on Embodiment 2 of this invention. It is a timing chart which shows the whole operation | movement sequence in the ignition device of the internal combustion engine which concerns on Embodiment 2 of this invention. It is a figure which shows the structure of the ignition device of the internal combustion engine which concerns on Embodiment 3 of this invention. It is a timing chart which shows the whole operation | movement sequence in the ignition device of the internal combustion engine which concerns on Embodiment 3 of this invention. It is a circuit diagram which shows the electric current control method in the ignition device of the internal combustion engine which concerns on Embodiment 3 of this invention.

  Preferred embodiments of an ignition device for an internal combustion engine according to the present invention will be described below with reference to the accompanying drawings. The present invention is not limited to the embodiments.

Embodiment 1 FIG.
1 is a diagram showing a configuration of an internal combustion engine ignition device according to Embodiment 1 of the present invention. In FIG. 1, one end of an energy storage coil 3 is connected to a DC voltage source 1 such as a battery or a DC / DC converter via a current detection means 2. The other end of the energy storage coil 3 is connected to a switch S1 that is a first switch means. The current detection means 2 detects a current flowing through the energy storage coil 3, and a current detector using a current detection resistor or a Hall element, a current transformer, or the like can be used. Alternatively, a detection winding may be added to the energy storage coil 3.

  The other end of the energy storage coil 3 is further connected in parallel with the switch S1 to a series circuit of the diode D1, the primary winding of the ignition coil 4, and the switch S2 as the second switch means. An ignition start capacitor 5 is connected to a connection point between the diode D 1 and the ignition coil 4, and an ignition plug 6 is connected to a secondary winding of the ignition coil 4. Furthermore, a series circuit of a diode D2 and a switch S3 as third switch means is connected to both ends of the energy storage coil 3. The series circuit of the diode D2 and the switch S3 constitutes a reverse current blocking type switch and is a bypass means having a third switch means. The energy storage coil 3, the diode D2, and the switch S3 constitute an accumulated current return circuit that operates as described later. For the switch S1, the switch S2, and the switch S3, an IGBT, an FET, a bipolar transistor, or the like can be used.

  Control means for controlling the switch S1, the switch S2, and the switch S3, for example, the control circuit 7 includes an ignition command signal input from an external circuit such as an electronic control system (ECU), and energy storage output from the current detection means 2. Based on the coil current signal, ON / OFF of the switch S1, the switch S2, and the switch S3 is controlled. The ignition command signal is composed of a plurality of signal lines, and includes an ignition preparation signal and an ignition period signal described later. Alternatively, these signals may be combined and transmitted through a single signal line.

  The ignition device for an internal combustion engine according to the first embodiment is configured as described above. Next, the basic operation of each part will be described.

  In the configuration shown in FIG. 1, when the switch S1 is turned on, the voltage of the DC voltage source 1 is applied to both ends of the energy storage coil 3 via the switch S1, and the current of the energy storage coil 3 gradually increases. In other words, energy is gradually stored in the energy storage coil 3.

  The ignition start capacitor 5 is charged by a current output from the energy storage coil 3 as described later. If the switch S2 is turned on while the ignition start capacitor 5 is charged, a high voltage is applied to the spark plug 6 due to the boosting effect of the ignition coil 4. For example, assuming that the voltage of the ignition start capacitor 5 is 300 V, the primary winding number Np and the secondary winding number Ns of the ignition coil 4 are the winding ratio Nr = Ns / Np = 100, the secondary winding of the ignition coil 4 A voltage of 30 kV is generated on the line. Actually, a higher voltage of 35 to 40 kV is instantaneously applied to the spark plug 6 due to LC resonance due to the leakage inductance of the ignition coil 4 and stray capacitance. Using this voltage, ignition discharge can be started in the spark plug 6.

If the switch S1 and the switch S3 are turned off and the switch S2 is turned on in a state where a predetermined current is passed through the energy storage coil 3, the spark plug 6 has
{(Current of energy storage coil 3)-(Primary excitation current of ignition coil 4)} / Nr
... (Formula 1)
Current can flow.

  The energy storage coil 3 can be regarded as a constant current source whose current value changes slowly, and the primary side excitation current of the ignition coil 4 also increases slowly depending on the primary side inductance and the primary side voltage. The spark plug 6 can be supplied with a predetermined current that gradually decreases regardless of the impedance of the discharge. That is, this circuit has a constant current output characteristic. Since the spark plug 6 after starting the discharge exhibits a constant voltage characteristic of about 1 kV due to the characteristics of the discharge, in order to control the electric power supplied to the spark plug 6, such a constant current characteristic is necessary on the circuit side. It is.

If the switch S2 is turned off while the exciting current is supplied to the ignition coil 4, a current due to the exciting current can be supplied to the spark plug 6 by a so-called flyback operation. The current value at this time is the secondary conversion value of the excitation current, that is,
-(Primary excitation current of ignition coil 4) / Nr (Expression 2)
It is.

  Next, the accumulated current return circuit will be described. When the switch S1 and the switch S2 are turned off and the switch S3 is turned on while a current flows through the energy storage coil 3, the current output from the energy storage coil 3 is transmitted through the diode D2 and the switch S3. Flow in a loop back to. The voltage drop in this current path has only a slight voltage drop due to the ON voltage of the switch S3, the forward voltage of the diode D2, the voltage drop due to the winding resistance of the energy storage coil 3, and the wiring resistance. Therefore, the current of the energy storage coil 3 continues to flow with almost no change, and the energy stored in the energy storage coil 3 can be held. In this way, the current path flowing through the energy storage coil 3 does not include a power source or a load, and only the parasitic voltage drop (ideally zero) is used to maintain the current flowing through the energy storage coil 3. The coil current is referred to as “refluxing”.

  FIG. 2 is a diagram showing a circuit around the energy storage coil 3 in FIG. 1 and a part of the control circuit 7. By circulating the coil current, the current of the energy storage coil 3 is changed to around a predetermined target value. FIG.

  The current signal detected by the current detection means 2 is compared with the current target value Itgt by the hysteresis comparator 20. (In actuality, the detected current is converted into a voltage and compared with the current target value converted into a voltage. Here, the current value is directly compared with the target current value.)

  If the plus-side hysteresis width of the hysteresis comparator 20 is Ihp and the minus-side hysteresis width is Ihm, when the current detection value rises to Itgt + Ihp, the output of the hysteresis comparator 20 becomes L level, and when the current detection value falls to Itgt-Ihm, The output of the hysteresis comparator 20 becomes H level.

  The output of the hysteresis comparator 20 is logically ANDed with a signal Sig1 for instructing energy storage / holding by the AND circuit 21, and then controls on / off of the switch S1 via the gate driver 22. The switch S3 is turned on / off through the gate driver 23 using the signal Sig1 for instructing energy storage / holding as it is. Note that both the switch S1 and the switch S3 are turned on when the inputs of the gate drivers 22 and 23 are at the H level.

  FIG. 3 is a timing chart showing the operation of the circuit shown in FIG. In FIG. 3, IL indicates a waveform of a current flowing through the energy storage coil 3, and GS1 and GS3 indicate ON / OFF states of the switch S1 and the switch S3, respectively.

  When the signal Sig1 for commanding energy storage / holding rises to active (H level), the switch S1 and the switch S3 are simultaneously turned on, current flows along the current path A shown in FIG. 2, and the current of the energy storage coil 3 is Increasing gradually. When the current reaches Itgt + Ihp, the output of the hysteresis comparator 20 becomes L level, the switch S1 is turned off, and the energy storage coil current flows back along the current path B. Due to a slight voltage drop in the return path, the current gradually decreases. When the current decreases to Itgt-Ihm, the output of the hysteresis comparator 20 becomes H level, and the switch S1 is turned on again.

  By repeating such an operation, the energy storage coil current is held at a substantially constant value (Itgt−Ihm to Itgt + Ihp) near the current target value. In the above operation, the switch S3 is kept on during the on period of the switch S1, but the switch S3 may be on or off while the switch S1 is on.

Next, the operation sequence of the entire ignition operation by the ignition device for the internal combustion engine according to the first embodiment will be described based on FIG. 4 with reference to FIG.
In FIG. 4, an ignition preparation signal Cont1 and an ignition period signal Cont2 are digital signals that are part of the ignition command signal in FIG. GS1, GS2, and GS3 indicate the on / off states of the switch S1, the switch S2, and the switch S3, respectively. IL represents the current of the energy storage coil 3, IT1 represents the primary current of the ignition coil 4, and Io represents the current of the spark plug 6. Further, VC is a voltage of the ignition start capacitor 5, and it is assumed that the voltage vc1 is stored as an initial state. For example, vc1 is 300V.

  When the ignition preparation signal Cont1 rises at time t0, the switch S1 and the switch S3 are turned on, the current IL of the energy storage coil 3 is increased, and energy is stored. When the current IL of the energy storage coil 3 reaches (Itgt + Ihp) at time t1, the switch S1 is turned OFF and the current IL of the energy storage coil 3 is circulated. Thereafter, by repeating the accumulation and return of energy by the method described with reference to FIGS. 2 and 3 until time t2, the current IL of the energy storage coil 3 is maintained at a substantially constant value.

  When the ignition preparation signal Cont1 falls and the ignition period signal Cont2 rises at time t2, the switch S1 and the switch S3 are turned off, and the switch S2 is turned on, whereby the initial voltage vc1 of the ignition start capacitor 5 is changed to the ignition coil 4 Is applied to the primary side winding and is boosted to 30 to 40 kV by the ignition coil 4, whereby ignition discharge is started at the spark plug 6.

  Subsequently, the current IL flowing through the energy storage coil 3 flows through the primary winding of the ignition coil 4, the excitation current is stored in the ignition coil 4, and the current Io flows through the spark plug 6. When ignition discharge starts, a constant voltage characteristic of about 1 kV is obtained between the electrodes of the spark plug 6 due to the characteristics of the discharge, but a predetermined current that gradually decreases flows through the spark plug 6 due to the constant current output characteristic of this circuit. be able to.

  During the period from time t2 to time t3, the energy of the energy storage coil 3 is released, and the current IL of the energy storage coil 3 decreases. The released energy is used as discharge energy of the spark plug 6 and is stored as excitation energy of the spark plug 6, and a part is consumed by a parasitic resistance component of the circuit.

  At time t3, the switch S2 is turned off and the switch S1 and the switch S3 are turned on, so that energy is stored in the energy storage coil 3 again. At this time, since the primary side current IT1 of the ignition coil 4 is cut off, the excitation current flowing through the ignition coil 4 is output from the secondary side winding, and is supplied to the ignition plug 6 from time t2 to time t3. A current Io having the opposite polarity flows. As for the timing of time t3, the time from time t2 to time t3 may be a predetermined time, or the time when the value of the current Io of the spark plug 6 is detected and the time is reduced to a predetermined value. It may be determined as t3. When the current IL of the energy storage coil 3 increases and recovers to near the target value at time t4, the energy storage coil current is held by performing the reflux operation. As described above, the control means 7 causes the current to flow through the energy storage coil 3 by turning on the switch S1 during the OFF period of the switch S2, and turns off the switch S1 while the energy is stored in the energy storage coil 3. At the same time, control is performed that includes a period in which the current flowing through the energy storage coil 3 is circulated to the bypass means by turning on the switch S3.

  In the period from time t5 to time t6, the switch S1 and the switch S3 are turned off and the switch S2 is turned on similarly to the operation in the period from the time t2 to the time t3. The current IL flowing through the energy storage coil 3 flows through the primary winding of the ignition coil 4, the excitation current is stored in the ignition coil 4, and the current Io flows through the spark plug 6. However, since the charge of the ignition start capacitor 5 has already been released, unlike the period from time t2 to time t3, the operation of applying a high voltage to the spark plug 6 is not performed.

  Here, paying attention to the operation of the energy storage coil 3, the period from the time t3 to the time t5 is a period in which energy is stored in the energy storage coil 3, and is therefore referred to as an “energy storage period”. On the other hand, the period from time t5 to time t6 is a period in which energy is released from the energy storage coil 3, and is therefore referred to as an “energy release period”.

  Focusing on the operation of the ignition coil 4, the period from the time t3 to the time t5 is a period for performing a so-called flyback operation in which the excitation current of the ignition coil 4 is output, and is therefore referred to as a “flyback period”. On the other hand, during the period from time t5 to time t6, a current flows through the primary winding of the ignition coil 4, so that an output is obtained from the secondary winding of the ignition coil 4 and at the same time the excitation current increases. Since this is a period during which the operation is performed, it is referred to as a “forward period”.

  Thereafter, by repeating the same operation from time t3 to time t6 a plurality of times, a current Io whose polarity is reversed can be continuously passed through the spark plug 6. In other words, by performing control to repeatedly turn on and off the switch S2, it is possible to give a positive and negative current to the spark plug 6.

  When the ignition period signal Cont2 falls at time t7 and the end of the repetitive operation is commanded, all of the switches S1, S2, and S3 are turned off at the end time t8 of the next energy storage period. Then, the output current IL of the energy storage coil 3 flows into the ignition start capacitor 5, and the ignition start capacitor 5 is charged to the same value as the initial value, and a series of operations is completed.

  In the above operation, the period from the time t3 to the time t5 is the energy discharge period when focusing on the operation of the energy storage coil 3, as described above, and is the forward period when focusing on the operation of the ignition coil 4. That is, different operations are performed in the same period in different parts of the circuit. Only one of the operating periods cannot be extended or shortened.

  Similarly, the period from time t5 to time t6 is the energy accumulation period and at the same time the flyback period, and the length of one period cannot be varied independently.

  In the conventional method in which the switch S3 is not provided and the reflux operation is not performed, all operations cannot be maintained optimally due to such a restriction. This problem will be described with reference to FIGS.

5 and 6 show a conventional multi-ignition operation sequence. FIG. 5 shows a case where the voltage of the input DC voltage source is high and FIG. 6 shows a case where it is low.
When attention is paid to the operation of the ignition coil 4 during the repetition period, in order to keep the spark plug current equal in the forward period and the flyback period, the increase in the excitation current in the forward period and the decrease in the excitation current in the flyback period. It is necessary to keep the width equal. Since the voltage applied to the ignition coil 4 is maintained at a substantially constant value regardless of the polarity due to the constant voltage characteristic of the ignition plug 6, the absolute value | di / dt | of the increase / decrease speed of the excitation current is constant, In order to keep the increase width and decrease width of the excitation current equal, the forward period and the flyback period need to have the same time width.

  On the other hand, paying attention to the energy storage coil 3, the rate of current decrease during the energy release period depends on the amount of energy released, that is, the output power. Therefore, if the output power is constant, the current decrease rate is constant. However, the rate of increase in current during the energy storage period depends on the input voltage. When the input voltage is high, the rate of increase is large, and when the input voltage is low, the rate of increase is small. Therefore, when the forward period and the flyback period are set to the same time width, when the input voltage is high, the storage coil current gradually increases and the output current also increases as shown in FIG.

  When the input current is low, the storage coil current gradually decreases and the output current also decreases as shown in FIG. Thus, in the conventional method, the output current gradually increases or decreases depending on the input voltage, and cannot be kept constant. If the output current increases too much, energy used for ignition is excessively consumed, and wear of the electrode of the spark plug 6 is accelerated, resulting in a short life. Further, when the output current decreases, the required ignition energy cannot be obtained, and ignition failure may occur.

  In the ignition device for an internal combustion engine according to the first embodiment, as shown in FIG. 4, the storage coil 3 is operated regardless of the input voltage by performing two operations of the energy storage operation and the reflux operation in the energy storage period. It was possible to keep the current of a predetermined value. As a result, since the output current to the spark plug 6 can be maintained at a predetermined value, it is possible to perform reliable ignition without consuming excess energy while extending the life of the spark plug 6. .

Embodiment 2. FIG.
Next, an internal combustion engine ignition device according to Embodiment 2 of the present invention will be described. In the first embodiment, by performing the reflux operation, it is possible to keep the storage coil current at a predetermined value regardless of whether the input voltage is high or low. However, this voltage range is also limited. That is, the recirculation operation is performed after the coil current reaches the target value. When the input voltage is very low, the coil current does not reach the target value during the energy storage period, and the stored coil current does not reach the target value. It may decrease gradually.

  Therefore, the ignition device for an internal combustion engine according to the second embodiment increases the current increase rate in the energy storage operation by providing a lead wire (intermediate tap) on the energy storage coil and connecting the switch S1 to the intermediate tap. It is a thing.

  FIG. 7 is a diagram showing a configuration of an ignition device for an internal combustion engine according to the second embodiment. The difference from FIG. 1 showing the first embodiment is only that the switch S1 is connected to the intermediate tap of the energy storage coil 70, and the other configurations are the same. Therefore, the current path during the energy storage operation is a path indicated as “current path A” in FIG.

Here, when the total number of turns of the energy storage coil 70 is Ne, the number of turns from the input (power supply side) to the intermediate tap is Ne1, and the total inductance is Le, the inductance Le1 from the input to the intermediate tap is
Le1 = Le × (Ne1 / Ne) ² (Formula 3)
It becomes.

FIG. 8 is a diagram showing an operation sequence of the entire ignition operation by the ignition device for the internal combustion engine according to the second embodiment. In FIG. 8, IL <b> 1 is a current that flows on the input side of the energy storage coil 70 and is a current detected by the current detection means 2. ILa is an output side converted value of the current of the energy storage coil 70, and when current is flowing in the current path A shown in FIG.
ILa = (Ne1 / Ne) × IL1 (Formula 4)
It becomes.

When the ignition preparation signal Cont1 rises at time t0 and the switches S1 and S3 are turned on, the current IL1 flowing through the energy storage coil 70 increases. In order to cause the target current Itgt to flow in the current path B in FIG.
IL1 = (Ne / Ne1) × Itgt (Formula 5)
It is necessary to pass such a current. Therefore, the first detection level of the hysteresis comparator (not shown) is
Is1 = (Ne / Ne1) × (Itgt + Ihp) (Formula 6)
(However, Ihp is the hysteresis width on the plus side of the hysteresis converter)
When the input side current reaches this value, it is assumed that the return operation is started.

When the recirculation operation is started, the current path is changed from the path A to the path B, the input side current value quickly becomes the same value (It2 + Ihp) as the output side converted current, and then starts to decrease more gradually. The second detection level Is2 of the hysteresis comparator is
Is2 = Itgt−Ihm (Expression 7)
If the current drops to this value and the switch means S1 is set to be turned on again, the output side converted value ILa of the energy storage coil current is (Itgt−Ihm) to (Itgt + Ihp) as in the first embodiment. ) Falls within a nearly constant value.

The current gradient d (IL1) / dt when energy is stored in the current path A in the energy storage coil 70 is defined as VL as the voltage applied to the inductance.
d (IL1) / dt = VL / Le1 = (VL / Le) × (Ne / Ne1) ²
(Equation 8)
It becomes. That is, without using an intermediate tap, compared with the case where inductance applies a voltage VL to the energy storage coil 70 is Le, ^twice (Ne / ^Ne1). When this is converted into the output side current value ILa,
d (ILa) / dt = (Ne1 / Ne) × d (IL1) / dt
= (Ne / Ne1) × VL / Le (Equation 9)
It becomes. That is, the output current conversion value of the energy storage coil current increases at a speed that is Ne / Ne1 times that when the intermediate tap is not used. For example, if Ne1 = Ne / 2, ILa increases at a gradient twice that when no intermediate tap is used, and reaches the target in 1/2 time.

  Therefore, even when the input voltage is very low, the target current can be reached in a relatively short time by providing the energy storage coil 70 with an intermediate tap. When the input voltage is high, the current may be held by the recirculation operation. Therefore, in the second embodiment, the energy storage coil current and the current of the spark plug 6 are maintained at predetermined values even in a wider input voltage range. be able to. When the ignition device according to Embodiment 2 is used for an internal combustion engine of an automobile, the battery voltage of the automobile varies in a wide range, for example, 6V to 16V. It is possible to ignite stably without changing.

Embodiment 3 FIG.
Next, an internal combustion engine ignition device according to Embodiment 3 of the present invention will be described. FIG. 9 is a diagram showing a configuration of an ignition device for an internal combustion engine according to the third embodiment. As shown in FIG. 9, in the ignition device for an internal combustion engine according to the third embodiment, a switch S1 is connected to a lead-out line on the way of the energy storage coil 70, and a diode D3 and a fourth diode are connected to the output terminal of the energy storage coil 70. A series circuit is connected to the switch S4 which is the switch means. In other configurations, parts that are the same as or equivalent to those in Embodiment 1 or Embodiment 2 are denoted by the same reference numerals, and description thereof is omitted.

  As described in the second embodiment, when the switch S1 connected to the lead-out line on the way of the energy storage coil 70 is turned on, Ne / Ne1 is compared to the case where the switch S4 connected to the output terminal of the energy storage coil 70 is turned on. Output side converted current increases at double speed.

  Therefore, the energy storage period is a period in which the switch S1 is turned on (the switch S4 is turned on or off) (a period in which the coil current increases rapidly and the energy stored in the energy storage coil 70 increases rapidly), and the switch The reached current value is adjusted by combining with a period in which only the switch S4 is turned on and the switch S1 is turned off (a period in which the coil current gradually rises and energy stored in the energy storage coil 70 gradually increases). Is possible.

  FIG. 10 is a diagram showing an operation sequence of the entire ignition operation by the ignition device for the internal combustion engine according to the third embodiment. In FIG. 10, when the switch S1 is turned on at time t0 (the switch S4 may be turned on or off), a current flows through the current path A2 shown in FIG. 9, and the secondary side converted value of the energy storage coil current suddenly increases. Increase. The diode D3 has a function of preventing a reverse voltage from being applied to the switch S4 during this period.

  When the switch S1 is turned off and the switch S4 is turned on at time t1, a current flows along the current path A1 shown in FIG. 9, and the secondary-side converted value of the storage coil current gradually increases. Although the accumulated energy release period starts at time t2, the current arrival value at time t2 can be controlled at the timing of time t1. That is, assuming that the time width from time t0 to time t2 is constant, the reaching current value is lower as the timing at time t1 is earlier, and the reaching current value is higher as the timing is later. By appropriately controlling the timing at time t1, it is possible to match the reached value of the accumulated current with the target Itgt.

The time t1 can be determined as follows. The slope of the coil current output side converted value ILa when a current is passed through the current path A1 in FIG.
d (ILa) / dt = (Vin−Vdrop) / Le (Equation 10)
It becomes. Here, Vin is the voltage of the DC voltage source 1, Vdrop is the total voltage drop due to the resistance component and switch means in the current path A 1, and Le is the total inductance of the energy storage coil 70.

Therefore, current ILa from time t1 to time t2 is expressed as follows as a function of time t.
ILa (t) = Itgt + ((Vin−Vdrop) / Le) × (t−t2)
... (Formula 11)
That is, if the current is made to coincide with ILa (t1) at time t1, then the target current Itgt is reached at time t2 according to Equation 11.

When Expression 11 is converted into the input side current IL1 of the energy storage coil 70,
IL1 (t) = [Itgt + {(Vin−Vdrop) / Le} × (t−t2)]
× (Ne / Ne1) (Equation 12)
It becomes.

Therefore, using the circuit shown in FIG. 11, the comparison current Iref with the current detection value is
Iref (t) = [Itgt + {(Vin−Vdrop) / Le} × (t−t2)]
× (Ne / Ne1) (Equation 13)
If the slope waveform is such that the comparison current Iref between the input side current IL1 of the energy storage coil 70 and the current detection value coincides at time t1, the switch S1 is turned off. Thereafter, the output side converted value of the coil current rises gently according to Equation 11, and reaches the target current Itgt at time t2. In FIG. 11, reference numeral 110 denotes a gate driver, and reference numeral 111 denotes a comparative current reference value generator.

  In the energy accumulation period after the start of ignition (the period from time t3 to time t5 and the equivalent part of the subsequent repetition period), the same operation as that in the period from time t0 to time t1 is performed. Therefore, if Iref (t) shown in FIG. 11 is a sawtooth waveform such as a broken line drawn on the waveform of IL1 in FIG. 10, the current value IL is always set to the target current at the end of the energy storage period. It can be adjusted to Itgt. Since Iref (t) is also a function of the input voltage Vin, it is only necessary to detect the input voltage as shown in FIG. 11 and change the slope of the sawtooth wave according to the voltage.

  As described above, in the ignition device for an internal combustion engine according to the third embodiment, the reaching value of the energy storage current can be controlled to a predetermined value without using the recirculation operation. Even in a wide input voltage range, the storage coil current and the spark plug current can be maintained at predetermined values.

  In addition, the switch S3 in the first and second embodiments has one end connected to the hot side (plus side) of the power supply, and when an IGBT or FET is used as the switch, the gate is based on the hot side potential. Since it is necessary to generate a waveform, the gate driving circuit becomes complicated. On the other hand, since both ends of the switch S4 and the switch S1 in the third embodiment are connected to the ground potential, the gate voltage may be given with an amplitude of about 0 to +15 V with respect to the ground potential. Can be configured easily.

DESCRIPTION OF SYMBOLS 1 DC voltage source 2 Current detection means 3, 70 Energy storage coil 4 Ignition coil 5 Ignition start capacitor 6 Spark plug 7 Control circuit 20 Hysteresis comparator 21 AND circuit 22, 23, 110 Gate driver 111 Comparison current reference value generator S1, S2, S3, S4 Switch D1, D2, D3 Diode

Claims (4)

An energy storage coil with one end connected to a power source;
First switch means connected to a lead wire in the middle of the energy storage coil;
One end of the primary winding is connected to the other end of the energy storage coil via a diode, and an ignition coil having a spark plug connected to the secondary winding;
Second switch means connected to the other end of the primary winding of the ignition coil;
A fourth switch means connected to the other end of the energy storage coil;
Control means for controlling the first switch means, the second switch means, and the fourth switch means,
The control means includes
In order to give a positive and negative current to the spark plug, the second switch means is repeatedly turned on / off,
In the off period of the second switch means, the first switch means is turned on to rapidly increase the energy stored in the energy storage coil, and the first switch means is turned off. An ignition device for an internal combustion engine, characterized by performing control having a period of gradually increasing the energy stored in the energy storage coil by turning on the fourth switch means.   The current arrival value of the current flowing through the energy storage coil is adjusted by combining a period in which the energy stored in the energy storage coil is rapidly increased and a period in which the energy stored in the energy storage coil is gradually increased. The internal combustion engine ignition device according to claim 1. Current detection means for detecting a current flowing through the energy storage coil;
Before the current value detected by the current detection means reaches the current arrival value, the energy stored in the energy storage coil is gradually increased from the control for rapidly increasing the energy stored in the energy storage coil. The ignition device for an internal combustion engine according to claim 2, wherein the ignition device is switched to control. Current detection means for detecting a current flowing through the energy storage coil;
A comparison current determined based on a slope waveform of a current flowing through the energy storage coil in a period of slowly increasing the current arrival value and the energy stored in the energy storage coil, and a current value detected by the current detection means The ignition device for an internal combustion engine according to claim 2, wherein the first switch means is turned off when and coincide with each other.

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