JP6581542B2 - Ignition control device for internal combustion engine - Google Patents

Description

  The present invention relates to an ignition control device that controls ignition in an internal combustion engine.

  As a technique related to an ignition control device for an internal combustion engine, for example, in Patent Document 1 (Japanese Patent Laid-Open No. 8-335522), an ignition coil flows in accordance with an ignition control signal output from an internal combustion engine electronic control device (ECU). In an internal combustion engine ignition device in which a primary current is energized and cut-off controlled by a switching circuit using a semiconductor such as a transistor and a high voltage is generated on the secondary side thereof, the switching circuit portion is an insulated gate bipolar transistor (IGBT) having a vertical structure. In the one-chip igniter IC that integrates the current limit function as a protection function and a thermal shut-off circuit that detects the heat generation of the chip and forcibly cuts off the power when abnormal heat is generated in the IGBT chip. The element is composed of a PN junction diode in a vertical IGBT structure, and a protection circuit is constructed. It is disclosed that in the transistor in the PNP bipolar transistor yelling made in the vertical IGBT structure.

JP-A-8-335522

  An ignition device for an internal combustion engine is provided with a function of restricting the current flowing through the primary coil that constitutes the ignition coil to suppress the occurrence of an abnormal current.

  However, in the above prior art, the limit value of the current flowing through the primary side coil is set by the components formed in the chip and cannot be changed (that is, a fixed value). Since the specification of the limit value of the current flowing to the primary coil side differs depending on the usage situation, if the limit value of the current is a fixed value as in the above-described conventional technology, the chip must be designed and manufactured for each different specification. There is a problem. In addition, even if the chip is configured such that the current limit value can be changed from the outside, it is necessary to newly provide a setting terminal for setting the limit value, which increases the number of terminals. is there.

  The present invention has been made in view of the above, and provides an ignition control device for an internal combustion engine capable of changing a limit value of a current flowing in a primary coil without newly providing a setting terminal. With the goal.

  In order to achieve the above object, the present invention performs switching so as to energize and cut off the current flowing in the primary coil constituting the ignition coil based on the ignition signal output from the electronic control device that controls the internal combustion engine. An ignition control device for an internal combustion engine that controls a circuit and generates a high voltage in a secondary coil constituting the ignition coil, wherein the current in the primary coil superimposed on an ignition signal from the electronic control device A setting discriminating circuit for discriminating limit setting information; a current limiting threshold value is set based on the current limiting setting information discriminated by the setting discriminating circuit; and a current flowing through the primary coil based on the current limiting threshold value It is assumed that a current limiting circuit for limiting is provided.

  According to the present invention, the limit value of the current flowing through the primary coil can be changed without newly providing a setting terminal.

1 is a diagram schematically showing an overall configuration of an ignition control device for an internal combustion engine according to a first embodiment. FIG. It is a figure which shows schematically the structure of the threshold value selection circuit which concerns on 1st Embodiment. It is a figure which shows typically an example of the time change of the voltage of the ignition signal input into an ignition control apparatus from an electronic control apparatus. It is a figure which shows typically an example of the time change of the electric current which flows into the primary side coil of an ignition coil according to the input to the ignition control apparatus of the ignition signal of FIG. It is a figure which shows schematically the structure of the threshold value selection circuit which concerns on the modification of 1st Embodiment.

  Embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
A first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a diagram schematically showing an overall configuration of an ignition control device for an internal combustion engine according to the present embodiment, together with its peripheral configuration.

  In FIG. 1, an ignition control device 100 for an internal combustion engine configures an ignition coil 19 of an ignition device 101 based on an ignition signal output from an electronic control unit (ECU: Electronic Control Unit) 10 that controls the internal combustion engine. The driving of the switching circuit 16 is controlled so that the current flowing through the primary coil 17 is turned on and off, and a high voltage is generated in the secondary coil 18 constituting the ignition coil 19.

  The ignition device 101 is disposed between an ignition coil 19 constituted by a primary side coil 17 and a secondary side coil connected to a power supply voltage (battery voltage) 7, and a primary side coil and a GND (reference potential) 70. Switching circuit 16, current detection resistor 20 disposed between switching circuit 16 and GND 70, and spark plug 21 disposed between the secondary coil and GND.

  The primary side coil 17 and the secondary side coil 18 of the ignition coil 19 form an electromagnetic induction coupling circuit, and the primary voltage generated in the primary side coil 17 by the mutual induction action and the primary side coils 17 and 2. A secondary voltage is generated in the secondary coil 18 in accordance with the turn ratio of the secondary coil 18. The switching circuit 16 connected to the primary coil 17 includes a power transistor such as an IGBT (Insulated Gate Bipolar Transistor) driven by an ignition signal input from the ignition control device 100, and the switching circuit 16 is turned on. When the switching circuit 16 is turned off (cut-off state) in a state in which the current flows through the primary coil 17 of the ignition coil 19 and the primary voltage is generated in the primary coil 17 and mutual induction occurs. Due to the action, a secondary voltage is generated in the secondary coil 18, and this secondary voltage is applied to the spark plug 21.

  The ignition control device 100 includes an input buffer circuit 11 for buffering (shaping / amplifying) the ignition signal output from the electronic control device 10 via the signal line 1 and outputting the signal via the signal line 2, and a signal line 3. An output buffer circuit 15 for buffering (shaping / amplifying) an ignition signal input via the signal line 4 and outputting the buffered signal to the switching circuit 16 via the signal line 4, and an ignition output from the electronic control unit 10 via the signal line 1 A threshold setting circuit 12 for determining the current limit setting information by determining the current limit setting information superimposed on the signal, the current limit threshold obtained from the threshold setting circuit 12 via the signal line 6, and the signal line 5 from the current detection resistor 20. The comparison circuit 13 that compares the primary side coil current detection voltage that is input via the signal line 2 and the signal voltage of the ignition signal that is connected between the signal line 2 and the signal line 2 and that is input via the signal line 2 are compared. It subtracted based on the comparison result of the road 13, and a level subtractor circuit 14 to be output to the output buffer circuit 15 via the signal line 3. Here, the current limit threshold is a threshold for setting an upper limit of a current value flowing through the switching circuit 16. The current limit setting information is information used for setting a current limit threshold.

  The electronic control device 10 can output two types of signals as a ignition signal, a Low signal (a signal of a voltage for shutting off the switching circuit 16) and a High signal (a signal of a voltage for energizing the switching circuit 16). Furthermore, a plurality of (three types in this embodiment) voltage signals (signal voltage Vs) can be output as the high signal, and current limit setting information is superimposed on the ignition signal due to the difference in the signal voltage Vs of the high signal. Has been.

  FIG. 2 is a diagram schematically showing the configuration of the threshold selection circuit.

  In FIG. 2, the threshold setting circuit 12 is generated by a threshold generation circuit 27 that generates a plurality of thresholds (in this embodiment, for example, thresholds A to C) that are candidates for the current limiting threshold, and the threshold generation circuit 27. One of the plurality of threshold values is selected as a current limit threshold value by the switches 28 to 30 and is output through the signal line 6 and the signal voltage Vs of the ignition signal input through the signal line 1 is used as a reference. Based on the comparison result of the comparators 22 and 23, the comparator 22 that compares the voltage 24 (Vth1), the comparator 23 that compares the signal voltage Vs of the ignition signal with the reference voltage 25 (Vth2), and switches 28 to 30 and a logic circuit 26 for switching 30.

  The logic circuit 26 selects any one of the thresholds A to C as the current limit threshold by switching the switches 28 to 30 of the selection unit 38 based on the combination of the comparison results from the comparators 22 and 23. . For example, if it is assumed that the reference voltage 24 (Vth1)> reference voltage 25 (Vth2), when the signal voltage Vs ≧ Vth1 of the ignition signal, Vs> Vth2 inevitably and the outputs of the comparators 22 and 23 are When Vth1> Vs ≧ Vth2, the output of the comparator 22 is Low and the output of the comparator 23 is High. When (Vth1>) Vth2> Vs, the outputs of the comparators 22 and 23 are Low. . Therefore, the thresholds A to C generated by the threshold generation circuit 27 are set in advance, and the logic circuit 26 sets the combination of the inputs (determination results) from the comparators 22 and 23 and the conditions for switching the switches 28 to 30. Thus, the current limit threshold value can be changed by the current limit setting information superimposed on the ignition signal as the difference in the signal voltage Vs.

  The comparison circuit 13 compares the current limit threshold value from the threshold setting circuit 12 with the primary side coil current detection voltage from the current detection resistor 20, and if the primary side coil current detection voltage is larger than the current limit threshold value, that is, When the value of the current flowing through the primary side coil of the ignition coil 19 is larger than the set value indirectly determined by the current limit threshold, subtraction according to the difference between the primary side coil current detection voltage and the current limit threshold The value is output to the level subtraction circuit 14 as a comparison result. The level subtraction circuit 14 subtracts (lowers) the ignition signal sent via the signal line 2 based on the subtraction value from the comparison circuit 13, thereby driving the driving voltage of the switching circuit 16 (switching circuit via the signal line 4). The voltage of the ignition signal sent to 16 is reduced, and the current flowing through the switching circuit 16 is limited. In other words, the current detection resistor 20, the comparison circuit 13, the output buffer circuit 15, and the switching circuit 16 cause the current flowing through the switching circuit 16 to be less than the current value indirectly set by the current limit threshold value. Is formed. When the primary coil current detection voltage is smaller than the current limit threshold, the subtraction value output from the comparison circuit 13 to the level subtraction circuit 14 is 0 (zero). The ignition signal is not subtracted.

  FIG. 3 is a diagram schematically showing an example of a temporal change in the voltage of the ignition signal input from the electronic control device to the ignition control device, where the vertical axis represents the ignition signal voltage and the horizontal axis represents the time. Show. FIG. 4 is a diagram schematically showing an example of a temporal change in the current flowing through the primary coil of the ignition coil in response to the input of the ignition signal of FIG. 3 to the ignition control device. The current value is shown on the horizontal axis.

  As shown in FIG. 3, in the present embodiment, an ignition signal having a voltage change as indicated by waveforms 31 to 33 is input from the electronic control device 10 to the ignition control device 100, and the signal voltage Vs of the High signal is Due to the difference, the current limit setting information is superimposed on the ignition signal. The limit value of the primary coil current corresponding to each of the waveforms 31 to 33 differs depending on the setting of the threshold setting circuit for the current limit setting information superimposed on the ignition signal as the voltage value of the High signal. Assuming that the limit value of the primary coil current set from the superimposed current limit setting information is I1, the value of the current flowing through the primary coil 17 changes as shown by the waveform 34 in FIG. Similarly, assuming that the current limit value of the primary coil set from the current limit setting information superimposed on the waveform 32 is I2, the current value flowing through the primary coil 17 is as shown by the waveform 35 in FIG. 4, assuming that the current limit value of the primary side coil set from the current limit setting information superimposed on the waveform 33 is I3, the current value flowing through the primary side coil 17 is the waveform 36 of FIG. To change. The waveform 37 shows how the current value changes when it is assumed that the current flowing through the primary coil is not limited.

  Here, the comparators 22 and 23 and the logic circuit 26 constitute a setting determination circuit that determines the current limit setting information of the primary coil superimposed on the ignition signal from the electronic control device 10. The threshold generation circuit 27, the switches 28 to 30, the comparison circuit 13, and the level subtraction circuit 14 set a current limit threshold based on the current limit setting information determined by the setting determination circuit, and based on the current limit threshold. A current limiting circuit for limiting the current flowing through the primary coil is configured.

  The operation of the present embodiment configured as described above will be described.

  When an ignition signal (High signal) is input from the electronic control device 10 to the ignition control device 100, the ignition signal is input to the switching circuit 16 via the input buffer circuit 11, the level subtraction circuit 14, and the output buffer circuit 15. The The switching circuit 16 is driven according to the voltage of the input ignition signal. At this time, the current of the primary side coil 17 of the ignition coil 19 is converted into a voltage (primary side coil current detection voltage) by the current detection resistor 20 and input to the comparison circuit 13. In the comparison circuit 13, the current limit threshold set by the threshold setting circuit 12 and the current detection resistor 20 based on the current limit setting information superimposed on the ignition signal input from the electronic control device 10 as the difference in voltage value of the High signal. Compare the voltage from. The level subtraction circuit 14 subtracts the voltage of the ignition signal input to the switching circuit 16 according to the comparison result in the comparison circuit 13, thereby reducing the current flowing through the switching circuit 16 to a current value equal to or lower than the current value corresponding to the current limit setting information. Limit to. At this time, the limit value of the current flowing through the switching circuit 16 can be changed by changing the current limit setting information superimposed on the ignition signal from the electronic control device 10.

  The effect of the present embodiment configured as described above will be described.

  An ignition device for an internal combustion engine is provided with a function of restricting the current flowing through the primary coil that constitutes the ignition coil to suppress the occurrence of an abnormal current. However, in the prior art, the limit value of the current flowing through the primary coil is set by components formed in the chip and cannot be changed (that is, a fixed value). Therefore, since the specification of the limit value of the current flowing to the primary coil side varies depending on the usage situation, if the limit value of the current is a fixed value as in the prior art, the chip must be designed and manufactured for each different specification. There was a problem of not becoming. In addition, even if the chip is configured such that the current limit value can be changed from the outside, it is necessary to newly provide a setting terminal for setting the limit value, which increases the number of terminals. there were.

  On the other hand, in the present embodiment, the current flowing through the primary coil 17 constituting the ignition coil 19 is turned on and off based on the ignition signal output from the electronic control device 10 that controls the internal combustion engine. In the ignition control device 100 for an internal combustion engine that controls the switching circuit 16 and generates a high voltage in the secondary coil 18 constituting the ignition coil 19, the primary side coil superimposed on the ignition signal from the electronic control device 10. Current limit setting information is determined, a current limit threshold is set based on the current limit setting information, and the current flowing through the primary side coil 17 is limited based on the current limit value. The limit value of the current flowing through the primary coil 17 can be changed without providing a new terminal.

  That is, the current limit value of the primary side coil 17 of the ignition coil 19 can be changed from the outside of the ignition control device 100. Further, for example, it can be applied in various situations such as performing an ignition operation at a desired current limit value or removing the current limit function depending on the temperature. Furthermore, even when products with different coil characteristics are handled, the current limit value on the primary side of the ignition coil can be set and changed without replacing hardware parts, so that the cost advantage can be improved.

  In the present embodiment, the case where the current limit setting information is superimposed using three kinds of voltages as the high signal of the ignition signal input from the electronic control device 10 has been described as an example, but the present invention is not limited thereto. For example, the current limit setting information superimposed by the high signal having four or more types of voltage values may be determined.

<Modification of the first embodiment>
A modification of the first embodiment of the present invention will be described with reference to FIG.

  In the ignition control device, the current limit setting information is superimposed on the ignition signal due to the difference in the signal current of the high signal of the ignition signal input from the electronic control device 10 in the ignition control device.

  FIG. 5 is a diagram schematically showing a configuration of a threshold selection circuit according to this modification. In the figure, the same members as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In FIG. 5, the threshold value setting circuit 12 </ b> A is generated by a threshold value generation circuit 27 that generates a plurality of threshold values (in this embodiment, for example, threshold values A to C) that are candidates for the current limit threshold value, and the threshold value generation circuit 27. One of a plurality of threshold values is selected as a current limit threshold value by the switches 28 to 30, and the selection unit 38 that outputs the signal via the signal line 6 and the signal current Is of the ignition signal that is input via the signal line 1 are voltage A resistor 41 for converting to a signal voltage Vs, a comparator 22 for comparing the signal voltage Vs of the ignition signal converted by the resistor 41 with a reference voltage 24 (Vth1), and a signal voltage Vs of the ignition signal The comparator 23 that compares with the reference voltage 25 (Vth2), and the logic circuit 26 that switches the switches 28 to 30 of the selection unit 38 based on the comparison results of the comparators 22 and 23. It is equipped with a.

  The electronic control device 10 can output two types of signals as the ignition signal: a Low signal (a signal for current that interrupts the switching circuit 16) and a High signal (a signal for current that energizes the switching circuit 16). Furthermore, a plurality of current signals (signal current Is) can be output as the High signal, and current limit setting information is superimposed on the ignition signal due to the difference in the signal current Is of the High signal.

  Other configurations are the same as those of the first embodiment.

  Also in this modified example configured as described above, the same effects as those of the first embodiment can be obtained.

  In addition, this invention is not limited to above-described embodiment and each Example, Various modifications and combinations are included. That is, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. Further, a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of a certain embodiment. In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment. In addition, control lines and signal lines are those that are considered necessary for the explanation, and not all control lines and signal lines are necessarily shown in the product.

1-6 Signal line 7 Power supply voltage (battery voltage)
10 Electronic control unit (ECU)
DESCRIPTION OF SYMBOLS 11 Input buffer circuit 12, 12A Threshold setting circuit 13 Comparison circuit 14 Level subtraction circuit 15 Output buffer circuit 16 Switching circuit 17 Primary side coil 18 Secondary side coil 19 Ignition coil 20 Current detection resistor 21 Spark plug 22, 23 Comparator 24, 25 Reference Voltage 26 Logic Circuit 27 Threshold Generation Circuit 28-30 Switch 31-37 Waveform 38 Selection Unit 41 Resistor 70 GND (Reference Potential)
100 Ignition Control Device 101 Ignition Device

Claims (3)

Based on an ignition signal output from an electronic control unit that controls the internal combustion engine, the switching circuit is controlled so as to energize and cut off the current flowing in the primary coil that constitutes the ignition coil, and the ignition coil is constituted 2 An ignition control device for an internal combustion engine that generates a high voltage in a secondary coil,
A setting discriminating circuit for discriminating current limit setting information of the primary coil superimposed on the ignition signal from the electronic control unit;
A current limit threshold is set based on the current limit setting information determined by the setting determination circuit, and based on a comparison result between the current limit threshold and a current detection voltage obtained by converting a current flowing through the primary coil into a voltage. An internal combustion engine ignition control device comprising: a current limiting circuit that controls a driving voltage of the switching circuit and limits a current flowing through the primary coil. The ignition control device for an internal combustion engine according to claim 1,
The ignition signal output from the electronic control device is composed of two types of high level and low level,
The ignition control device for an internal combustion engine, wherein the setting determination circuit determines the current limit setting information superimposed as a voltage value difference on a high-level ignition signal from the electronic control device. The ignition control device for an internal combustion engine according to claim 1,
The ignition signal output from the electronic control device is composed of two types of high level and low level,
The ignition control device for an internal combustion engine, wherein the setting determination circuit determines the current limit setting information superimposed as a difference in current value of a high-level ignition signal from the electronic control device.

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