JP2019183846A - Ignition apparatus - Google Patents

Abstract

To provide an ignition apparatus that limits a secondary superimposition current with a simple configuration.SOLUTION: A current flowing in a sub-primary coil 12 can be limited in an ignition apparatus. In the apparatus, a voltage generated in a secondary coil 15 at a time when a current in a main primary coil 10 is cut off generates a secondary current, and then the sub-primary coil 12 is energized so that a superimposition current is generated in the secondary coil 15; and a sub-IC 13 connected in series with the sub-primary coil 12 is pulse-controlled so that a current flowing in the sub-primary coil 12 is controlled and hence the superimposition current is controlled.SELECTED DRAWING: Figure 1

Description

  The present application relates to an ignition device attached to, for example, an internal combustion engine.

  In order to improve the fuel efficiency of internal combustion engines, leaner or higher EGR (Exhaust Gas Recirculation) internal combustion engines are being studied. However, since the air-fuel mixture of these internal combustion engines is not ignitable, the ignition device has high energy. In particular, there is a demand for higher current. Therefore, for example, as disclosed in Patent Document 1, another primary coil (sub 1) is added to the secondary side output that is output after blocking the current of the conventional primary coil (main primary coil). There has been proposed an ignition device that additionally superimposes output energy (current) from a secondary coil).

  In addition to the power supply voltage applied to the sub primary coil, the secondary superimposed current by the sub primary coil includes the voltage applied to the spark plug (plug resistance and current flowing therethrough, voltage between plug gaps) and the secondary voltage. It is known to be affected by a voltage drop caused by coil resistance. For this reason, if the secondary current is increased carelessly, the combustibility is satisfactory, but the secondary coil heat generation increases due to the increase in the secondary current, and the ignition device may be damaged, or energy (current) is supplied. This causes a problem that the spark plug gap terminal wears out.

  In order to limit (control) this current, for example, as disclosed in Patent Document 2, the switching element (sub IC) connected in series with the sub primary coil is pulse controlled (sub IC on / off). A device that controls the average value of the current flowing through the sub-primary coil by controlling (or PWM control) and controlling the secondary superimposed current has been proposed.

US Pat. No. 9,399,979 International Publication No. 2016/157541

  However, when the current flowing through the sub primary coil is controlled with high accuracy by the above-described method, it is necessary to switch the sub IC at a high speed. Therefore, it is necessary to select an element capable of high-speed switching. A loss will occur. In addition, when the sub IC is switched after the secondary current disappears by the main primary coil, a voltage having a polarity opposite to that of normal ignition is generated, and there is a risk of damaging the elements built in the ignition device. Is required.

  The present application has been made in order to solve the above-described problem, and an object thereof is to obtain an ignition device that limits the secondary superimposed current with a simple configuration.

An ignition device disclosed in the present application is connected to a main primary coil that generates a current-carrying magnetic flux in the forward direction when energized from a power supply and generates a reverse-direction magnetic flux by interrupting the current, and the main primary coil. A main switching element that switches between energization and interruption of the main primary coil, a sub primary coil that generates a magnetic flux in the same direction as the interruption magnetic flux by energization from a power source, and the sub primary coil, A sub-switching element that switches between energization and shut-off of the sub-primary coil and a secondary that is connected to a spark plug and is magnetically coupled to the main primary coil and the sub-primary coil to generate discharge energy A coil, and
A secondary current is generated by the voltage generated in the secondary coil at the timing when the main switching element is shut off, and then the sub primary coil is energized by energizing the sub switching element and superimposed on the secondary coil. While generating current,
The current flowing through the sub primary coil is limited by increasing the collector-emitter voltage of the sub switching element.

  According to the ignition device disclosed in the present application, by limiting the current flowing through the sub primary coil, it is possible to prevent the superimposed current from becoming excessively large when the power supply voltage or the ignition plug applied voltage varies.

1 is a circuit diagram showing an ignition device according to Embodiment 1. FIG. It is a figure which shows the operation | movement waveform in the normal state of the ignition device which concerns on Embodiment 1. FIG. It is a figure which shows the operation | movement waveform at the time of the electric current limitation of the ignition device which concerns on Embodiment 1. FIG. 6 is a circuit diagram showing an ignition device according to Embodiment 2. FIG.

  Hereinafter, an ignition device according to an embodiment of the present application will be described in detail with reference to the drawings. In each figure, the same reference numerals indicate the same or corresponding parts.

Embodiment 1 FIG.
1 is a circuit diagram showing an ignition device according to Embodiment 1. FIG. FIG. 2 is a diagram showing operation waveforms in the normal state of the ignition device shown in FIG. 1 (power supply voltage 13.5 V, normal temperature, spark plug voltage 1 kV). FIG. 3 is a diagram showing operation waveforms when the power supply voltage of the ignition device shown in FIG. 1 is increased (power supply voltage 16 V).

  As shown in FIG. 1, the ignition device according to Embodiment 1 is connected to a main primary coil 10 and one end of the main primary coil 10, and a main switching element that switches between energization and interruption of the main primary coil 10. (Hereinafter referred to as a main IC) 11, a sub primary coil 12, and a sub switching element (hereinafter referred to as a sub IC) which is connected to one end of the sub primary coil 12 and switches between energization and cutoff of the sub primary coil 12. .) 13 and one end of which is connected to the spark plug 14 and magnetically coupled to the main primary coil 10 and the sub primary coil 12 to generate a secondary coil 15 that generates discharge energy.

  The other ends of the main primary coil 10 and the sub primary coil 12 are connected to the same power supply 16. The main primary coil 10 is wound so as to have a polarity opposite to that of the secondary coil 15 when current is supplied from the power source 16, and the sub primary coil 12 is 2 when current is supplied from the power source 16. It is wound so as to have the same polarity as the next coil 15. In other words, the main primary coil 10 and the sub primary coil 12 are wound so as to have opposite polarities when viewed from the power source 16. Therefore, the main primary coil generates an energizing magnetic flux in the forward direction when energized, and generates a breaking magnetic flux in the reverse direction by interrupting the current. Further, the sub primary coil generates a magnetic flux in the same direction as the breaking magnetic flux when energized.

  The collector of the main IC 11 is connected to the main primary coil 10, and the emitter is connected to the GND 17. The collector of the sub IC 13 is connected to the sub primary coil 12, and the emitter is connected to the GND 17 via the current detection resistor 18. The voltage of the current detection resistor 18 is configured to be input to a gate control circuit 19 that controls the gate voltage of the sub IC 13. The voltage of the current detection resistor 18 is constant, that is, the current flowing through the sub primary coil 12 is The gate of the sub IC 13 is controlled so as to be constant.

Next, the operation of the ignition device according to Embodiment 1 will be described with reference to FIGS.
The waveforms in FIGS. 2 and 3 are respectively from the top of the drawing, the drive signal of the main IC 11, the current flowing through the main primary coil 10 (hereinafter referred to as the main primary current), the drive signal of the sub IC 13, and the sub primary coil 12. Is a secondary current obtained by adding the secondary current generated by the main primary coil 10 and the superimposed current generated by the sub primary coil 12. .

  FIG. 2 shows a normal operation waveform. The main primary coil 10 is energized and cut off in accordance with the on / off of the drive signal to the main IC 11. Due to the interruption of the main primary current, a large negative voltage is generated in the secondary coil 15 by mutual induction (not shown in FIG. 2). Due to this voltage, a discharge occurs between the gaps of the spark plug 14, and a negative current flows through the secondary coil 15. Here, the secondary current is positive in the direction of arrow A.

  Next, when the sub IC 13 is turned on, a current immediately flows through the sub primary coil 12 (current rise is fast), and then gradually increases. Along with this, a current corresponding to the turns ratio of the sub primary coil 12 and the secondary coil 15 is superimposed on the secondary current. Thereafter, the sub primary current is cut off by turning off the sub IC 13, and the superimposed current on the secondary current becomes zero.

Hereinafter, the present embodiment will be described with specific values. In the present embodiment, the voltage drop caused by the resistance of the secondary coil 15 at the start of energization of the sub IC 13 is designed to be about 1 kV. Therefore, the induced voltage of the secondary coil 15 is 2 kV, which is the sum of the voltage drop 1 kV and the spark plug voltage 1 kV.
Further, the turn ratio of the sub primary coil 12 and the secondary coil 15 is set to 200, and the induced voltage generated in the sub primary coil 12 is about 10V. Further, by setting the collector-emitter voltage of the sub IC 13 to about 2 V and the resistance of the sub primary coil 12 to about 0.2Ω, the sub primary current flows to about 10 A after the sub IC 13 is turned on, and then gradually decreases. Will increase. Corresponding to the sub primary current, a superimposed current of about 50 mA flows in the secondary current.

  On the other hand, FIG. 3 shows an operation waveform when the power supply voltage is increased. When the sub primary current is not limited, after the sub IC 13 is turned on, as shown by the broken line in FIG. As a result, a superposed current of about 90 mA flows in the secondary current as shown by the broken line in FIG. 3, and the superposed current greatly increases as the power supply voltage increases.

  For this reason, as shown in FIG. 1, when a current detection resistor 18 of about 10 mΩ, for example, is inserted on the emitter side of the sub IC 13, the voltage across the current detection resistor 18 can be set to 0.12 V, for example. That is, the gate control circuit 19 controls the gate voltage of the sub IC 13 so that the current flowing through the current detection resistor 18 becomes 12A. As a result, the collector-emitter voltage of the sub IC 13 is increased, and the superimposed current on the secondary current is limited to 60 mA. The resistance value of the current detection resistor 18 is set to be small, and the influence on the sub primary current is also suppressed to a small value. Further, if the current flowing through the current detection resistor 18 is set in the range of 10A to 20A, the sub primary coil 12 and sub Heat generation of the IC 13 can be prevented. Therefore, it is preferable to configure the current detection resistor 18 with a variable resistor.

  As described above, the ignition device according to Embodiment 1 can suppress the increase in the superimposed current when the power supply voltage is changed by increasing the collector-emitter voltage of the sub IC 13, and can increase the maximum secondary current. The value can be limited. Thereby, excessive heat generation of the secondary coil 15 can be prevented, and excessive wear of the spark plug 14 can be prevented.

  Further, since the current is not suppressed under the normal use condition shown in FIG. 2, a large amount of superimposed current can be secured even in the normal state. Further, since the upper limit of the current to be used is set to 12 A, it is possible to use another switching element having the same current capability as that of the main IC 11. Furthermore, since the superimposed current of the secondary current and the current flowing through the sub primary coil 12 can be reduced, the heat generation of the secondary coil 15 and the sub primary coil 12 can also be suppressed.

  In a normal state where the voltage of the power supply 16 or the voltage applied to the spark plug 14 does not fluctuate, the sub primary current is not limited by setting the current flowing through the sub primary coil 12 to an unrestricted state. Therefore, the output performance in the normal state is not limited.

  In addition, said numerical value is an example, You may restrict | limit to another value and although the polarity of the main primary coil 10 and the secondary coil 15 is made into the reverse polarity, it is good also as the same polarity. Further, although the main primary coil 10 and the sub primary coil 12 are connected to the same power source, they may be connected to different power sources (for example, 12V system and 24V system or 36V system). Further, by inputting internal combustion engine information (for example, air-fuel ratio or EGR (Exhaust Gas Recirculation) amount) to the gate control circuit 19, it becomes possible to set a limit value according to the operating condition of the internal combustion engine.

Embodiment 2. FIG.
FIG. 4 is a circuit diagram showing an ignition device according to the second embodiment. Since the basic circuit configuration, operation principle, and operation waveform are the same as those in the first embodiment, a duplicate description is omitted.
As shown in FIG. 4, in the ignition device according to the second embodiment, a current limiting resistor 20 that limits the sub primary current is connected between the sub primary coil 12 and the sub IC 13. In the second embodiment, the current detection resistor 18 and the gate control circuit 19 in the first embodiment are not provided. Other configurations are the same as those in the first embodiment.

The ignition device according to the second embodiment is configured as described above, and the present embodiment will be described below with specific values.
In the second embodiment, when the energization of the sub IC 13 is started, the voltage drop caused by the resistance of the secondary coil 15 is designed to be about 0.5 kV, and a plug with a built-in resistor is assumed as the spark plug 14 to be connected. The voltage between the gaps is assumed to be 1 kV, and the voltage drop due to the built-in resistor is assumed to be about 0.5 kV. Therefore, the induced voltage of the secondary coil 15 is 2 kV, which is the sum of the voltage drop 1 kV and the spark plug voltage 1 kV.
Further, the turn ratio of the sub primary coil 12 and the secondary coil 15 is set to 200, and the induced voltage generated in the sub primary coil 12 is about 10V. Further, the collector-emitter voltage of the sub IC 13 is set to about 2V, and the resistance of the sub primary coil 12 is set to about 0.2Ω.

  When the current limiting resistor 20 is not provided, the sub primary current is about 10 A and the assist current is about 50 mA as in the first embodiment, but in the present embodiment, the sub primary current flows along the path. Since the current limiting resistor 20 is inserted and its resistance value is 0.3Ω, the current flowing through the sub primary coil 12 is reduced to about 4A. Accordingly, the secondary superimposed current becomes 20 mA.

Since the assist current decreases due to the insertion of the current limiting resistor 20, it is necessary to make the current values after superposition equal by increasing the secondary current generated by the main primary coil 10 that is the superposition source, for example. .
On the other hand, for example, when the spark plug 14 to be used is changed to become a non-resistance spark plug (built-in resistance is 0 kΩ), the voltage drop due to the built-in resistance is eliminated, so that the induced voltage generated in the secondary coil 15 is Along with this, the induced voltage generated in the main primary coil 10 or the sub primary coil 12 also decreases. Thereby, the voltage applied to the sub primary coil 12 increases, and the sub primary current increases.

  Without the current limiting resistor 20, the built-in resistance of the spark plug 14 is eliminated, so that the current flowing through the sub primary coil 12 increases to about 16 A (increase of 6 A), and accordingly, the assist current becomes about 80 mA. The total of the secondary current and the superimposed current is increased by 30 mA compared to the case where there is a resistance. On the other hand, in the case of the present embodiment in which the current limiting resistor 20 is inserted, the sub primary current increases to about 7 A (increase of 3 A) by eliminating the built-in resistance of the spark plug 14, and the assist current is about 40 mA accordingly. It becomes. For this reason, the secondary current and the superimposed current are increased by about 15 mA compared to when the spark plug 14 has resistance.

  As described above, by inserting the current limiting resistor 20 in the path of the sub primary current, it is possible to suppress the increase amount of the sub primary current and reduce the increase amount of the superimposed current and the secondary current. Can do. Further, since the sub primary current can be suppressed by the current limiting resistor 20 without increasing the collector-emitter voltage of the sub primary coil 12 and the sub IC 13, the heat generation of the sub primary coil 12 and the sub IC 13 is also suppressed. For example, an IC having a small heat capacity can be used as the sub IC.

  In the second embodiment, the secondary current by the main primary coil 10 is increased in order to compensate for the decrease in the superimposed current when the current limiting resistor 20 is inserted. For example, the resistance value of the secondary coil 15 is decreased. Alternatively, it may be possible to ensure the same superimposed current as when the current limiting resistor 20 is not inserted, for example, by increasing the turn ratio.

  Further, although the current limiting resistor 20 is inserted between the sub primary coil 12 and the sub IC 13, there is no problem as long as only the sub primary current flows, for example, between the sub IC 13 and the GND 17. Further, the current limiting resistor 20 may be a variable resistor. For example, in this case, the current limiting resistor 20 is set to zero Ω in an assumed normal state, and the resistance is increased when the voltage between the gaps of the spark plug 14 changes (when the voltage decreases). You may control as follows. Similarly to the first embodiment, in the normal state where the voltage of the power supply 16 or the voltage applied to the spark plug 14 does not fluctuate, if the current flowing through the sub primary coil 12 is set to an unrestricted state, the sub primary current Therefore, the output performance in the normal state is not limited.

This application describes various exemplary embodiments and examples, but the various features, aspects, and functions described in one or more embodiments can be adapted to the application of a particular embodiment. The present invention is not limited and can be applied to the embodiments alone or in various combinations.
Accordingly, innumerable modifications not illustrated are envisaged within the scope of the technology disclosed in the present application. For example, the case where at least one component is deformed, the case where the component is added or omitted, the case where the at least one component is extracted and combined with the component of another embodiment are included.

10 main primary coil, 11 main switching element (main IC), 12 sub primary coil, 13 sub switching element (sub IC), 14 spark plug, 15 secondary coil, 16 power supply, 17 GND, 18 current detection resistor, 19 Gate control circuit, 20 Current limiting resistor.

Claims (4)

A main primary coil that generates an energizing magnetic flux in the forward direction by energizing from the power source and generates a reverse interrupting magnetic flux by interrupting the current is connected to the main primary coil, and is connected to the main primary coil. A main switching element that switches between energization and interruption; a sub primary coil that generates a magnetic flux in the same direction as the interruption magnetic flux by energization from a power source; and an energization to the sub primary coil connected to the sub primary coil. A sub-switching element that switches off, and a secondary coil that is connected to a spark plug at one end and is magnetically coupled to the main primary coil and the sub-primary coil to generate discharge energy;
A secondary current is generated by the voltage generated in the secondary coil at the timing when the main switching element is shut off, and then the sub primary coil is energized by energizing the sub switching element and superimposed on the secondary coil. While generating current,
An ignition device characterized in that a current flowing through the sub primary coil is limited by increasing a collector-emitter voltage of the sub switching element.   The ignition device according to claim 1, wherein the collector-emitter voltage of the sub-switching element is variable.   3. The ignition device according to claim 2, wherein in a normal state in which the voltage of the power source or the voltage applied to the spark plug does not vary, the current flowing in the sub primary coil is set to an unrestricted state.   The ignition device according to any one of claims 1 to 3, wherein a limit value of a current flowing through the sub primary coil is set from 10A to 20A.

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