JP2017172557A - Ignitor of internal combustion engine - Google Patents

Abstract

To improve ignition performance and protect a spark plug.
An ignition device provided in an engine having a multiple ignition system, wherein an engine control unit 10 sets the number of ignitions Nign in one cycle based on the operating state of the engine. A setting unit 13; an ignition determination unit 14 that determines ignition in the cylinder of the engine; Have
[Selection] Figure 1

Description

  The present invention relates to ignition control of an internal combustion engine.

In an internal combustion engine having an ignition device such as a gasoline engine, a device for determining a cylinder that misfires during operation of the internal combustion engine has been proposed.
An ignition device for an internal combustion engine includes, for example, an ignition coil and an ignition plug. A pulse current is caused to flow on the primary side of the ignition coil and a high-voltage pulse wave is generated on the secondary side between the electrodes of the ignition plug. Let spark discharge.

  Further, Patent Document 1 discloses a device that detects a secondary voltage applied between electrodes of a spark plug and determines misfire based on the attenuation characteristic of the secondary voltage. In Patent Document 1, when the decay time of the secondary voltage is relatively short and falls rapidly, it is normally ignited, and when the decay time of the secondary voltage is relatively long and slow, it is misfired. judge.

Japanese Patent No. 2535699

  By the way, in recent years, internal combustion engines with enhanced in-cylinder flow have been developed in order to realize rapid combustion in lean burn engines, EGR introduction engines, and the like. Furthermore, in such an internal combustion engine with enhanced in-cylinder flow, power is alternately supplied to one plug with two coils so as to improve ignition performance in response to blow-off of ignition discharge, and the number of discharges A multi-ignition system with an increased value has been studied.

However, in the multiple ignition system, the number of times of ignition increases in one start, and therefore there is a problem that the electrode of the spark plug is consumed quickly. In particular, if ignition is repeated even after the air-fuel mixture in the cylinder is ignited, the discharge is performed under a high temperature condition, so that the temperature of the electrode rises and becomes more easily consumed.
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an ignition device for an internal combustion engine that improves ignition performance and suppresses consumption of a spark plug.

  In order to achieve the above object, the ignition device according to claim 1 is provided in an internal combustion engine including a multiple ignition system that ignites a plurality of times with one spark plug in one cycle, and the operating state of the internal combustion engine. An ignition number setting unit that sets the number of ignitions in one cycle based on the above, an ignition determination unit that determines ignition in the cylinder of the internal combustion engine, and one cycle when the ignition determination unit determines the ignition And an ignition control unit that suppresses ignition more than the number of times of ignition.

Preferably, the ignition control unit may perform the suppression of the ignition when the ignition determination is made in a predetermined operation region where the in-cylinder flow of the internal combustion engine is equal to or greater than a predetermined value.
Preferably, the number-of-ignitions setting unit sets multiple ignitions for suppressing the number of ignitions in one cycle based on the ignition determination based on an operating state of the internal combustion engine and a predetermined number of times without performing the ignition determination. Switch to fixed ignition to fix.

Preferably, the ignition frequency setting unit may fix the ignition frequency to the predetermined number in an operation state in which the inside of the cylinder is in a predetermined high temperature region.
Preferably, the ignition control unit may suppress the ignition after determining the ignition and igniting a predetermined number of times.
Preferably, a learning control unit that executes learning control for reflecting the number of ignitions when the ignition determination unit determines the ignition in the number of ignitions set in the ignition number setting unit in the next and subsequent cycles may be provided.

  In the ignition device for an internal combustion engine according to the present invention, ignition is suppressed more than the number of ignitions in one cycle when the ignition is determined, so that ignition after ignition can be suppressed. As a result, the ignition plug can be protected by suppressing useless ignition after ignition, while improving the ignition performance by a multiple ignition system that ignites a plurality of times with one ignition plug in one cycle.

It is a block diagram of the ignition device of one Embodiment of this invention. It is a flowchart which shows the ignition frequency control point of 1st Embodiment. It is an example of an ignition frequency setting map. It is a graph which shows an example of transition of the secondary voltage and secondary current at the time of ignition judgment. It is a flowchart which shows the ignition frequency control point of 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of an ignition device according to an embodiment of the present invention. FIG. 1 shows a configuration of an ignition device in one cylinder.
An engine including an ignition device 1 according to an embodiment of the present invention is, for example, a multi-cylinder gasoline engine for driving driving of an automobile.

FIG. 1 shows a configuration of an ignition device 1 in one cylinder.
As shown in FIG. 1, an ignition device 1 according to the present embodiment includes an ignition plug 2 (igniter) provided in each cylinder, ignition coils 3a and 3b provided in each cylinder, and an ignition coil. An engine control unit 10 for controlling 3a and 3b is provided.
The ignition coils 3a and 3b include transistors 4a and 4b as switching elements that intermittently cut off the primary current. The in-vehicle battery 6 is connected to one end of the primary coils 5a and 5b of the ignition coils 3a and 3b, and the other end is connected to the collectors of the transistors 4a and 4b. The bases of the transistors 4a and 4b are connected to the engine control unit 10, and the emitters are grounded.

One ends of the secondary coils 7a and 7b of the ignition coils 3a and 3b are connected to the ignition plug 2 via diodes 8a and 8b. The other ends of the secondary coils 7a and 7b are grounded.
The primary current flows through the primary coils 5a and 5b connected to the collectors of the transistors 4a and 4b by the voltage applied as an ignition signal from the engine control unit 10 to the bases of the transistors 4a and 4b. At the ignition timing, the voltage applied to the transistors 4a and 4b is suddenly cut off, so that the primary current flowing through the primary coils 5a and 5b is suddenly reduced. Electric power is generated. Then, a high voltage is generated in the secondary coils 7a and 7b by the mutual induction action, and a spark discharge is generated in the electrode of the spark plug 2. Here, the secondary current flowing through the spark plug 2 is attenuated with time and becomes a triangular wave-like pulse current.

Two ignition coils 3a and 3b are connected to one spark plug 2, and power is supplied from each secondary coil 7a and 7b. The diodes 8a and 8b are provided so that a current flowing from one ignition coil (any one of 3a and 3b) does not flow to the other ignition coil (the other of 3a and 3b).
The engine control unit 10 alternately applies and shuts off ignition signals to the two ignition coils 3a and 3b, so that a high voltage is alternately applied from the ignition coils 3a and 3b to the ignition plug 2. Compared with an ignition device having only an ignition coil, a spark discharge twice as many times as the same time can be obtained.

  The engine control unit 10 includes an input / output device, a storage device (ROM, RAM, nonvolatile RAM, etc.), a timer, a central processing unit (CPU), etc., and an engine speed detected by the engine speed sensor 11. And other information such as the accelerator operation amount detected by the accelerator opening sensor 12 is input. Then, the engine control unit 10 controls the ignition by the spark plug 2 by outputting an ignition signal to each ignition coil 3a, 3b of each cylinder based on the various information.

Further, the engine control unit 10 controls the operation of various other engine equipment such as a fuel injection amount and fuel injection timing of a fuel injection valve (not shown), an electronic control throttle valve, an EGR valve, and the like based on the various information. Then, the engine operation is controlled.
Further, the engine control unit 10 controls ignition by an ignition frequency setting unit 13 that sets the multiple ignition frequency Nign based on the operating state of the engine, an ignition determination unit 14 that determines ignition in the cylinder of the engine, and ignition. An ignition control unit 15 and a learning control unit 16 that learns and controls the number of times of multiple ignition Nign are provided.

FIG. 2 is a flowchart showing the ignition frequency control procedure of the first embodiment executed in the engine control unit 10. FIG. 3 is an example of an ignition frequency setting map. FIG. 4 is a graph showing an example of transition of the secondary voltage and the secondary current at the time of ignition determination. FIG. 4 shows changes in the secondary voltage and the secondary current during one ignition.
The engine control unit 10 performs the ignition frequency control shown in FIG. 2 for each cylinder during engine operation.

In step S10, the engine control unit 10 first inputs the engine rotation speed Ne from the engine rotation speed sensor 11 and the accelerator opening θaps from the accelerator opening sensor 12, and calculates the target torque Tobj of the engine. Then, the process proceeds to step S20.
In step S20, the number of multiple ignitions Nign is obtained based on the engine speed Ne from the engine speed sensor 11 and the target torque Tobj calculated in step S10. The number of times of multiple ignition Nign is the number of times of ignition in one cycle, and is the number of triangular-wave pulses generated on the secondary coils 7a and 7b side. The number of times of multiple ignition Nign is obtained by reading a map as shown in FIG.

  As shown in FIG. 3, the multiple ignition number Nign is multiple ignition at two or more times at low rotation and low load (region of low rotation and low load from the broken line in FIG. 3), and multiple ignition is performed at high rotation or high load. The number of times Nign is one. Also, in the multiple ignition region, the multiple ignition number Nign is set to increase stepwise as the low rotational load becomes low between 2 and 5. Then, the process proceeds to step S30.

In step S30, it is determined whether or not the number of multiple ignitions Nign obtained in step S20 is greater than one. If the multiple ignition number Nign is greater than 1, the process proceeds to step S40. If the multiple ignition number Nign is 1 or less, the process proceeds to step S90.
In step S40, ignition is performed at the multiple ignition number Nign. In the present embodiment, since the two ignition coils 3a and 3b supply power alternately and ignite, the total number of ignition signals sent to the two ignition coils 3a and 3b in one cycle is The number of times of multiple ignition is set to Nign. Then, the process proceeds to step S50.

  In step S50, an ignition determination is performed. The ignition determination is performed by a secondary current flowing from the ignition coils 3a and 3b to the ignition plug 2 or a secondary voltage applied to the ignition plug 2. As shown in FIG. 4, when a secondary voltage of a high voltage is applied to the spark plug 2 and a spark discharge occurs between the electrodes of the spark plug 2, a secondary current flows in a triangular wave shape. That is, when the air-fuel mixture burns, ions generated by the combustion are generated between the electrodes. The secondary current temporarily varies due to the generation and movement of ions. Along with this, the secondary voltage also fluctuates rapidly. Therefore, the secondary current or the secondary voltage is monitored, and the presence or absence of ignition is determined based on the fluctuation. Then, the process proceeds to step S60.

  In step S60, the number of ignitions when it is determined that there is ignition in S50 is stored in the storage device as the number of ignitions Mign in association with the operating point at that time (target torque Tobj and engine speed Ne). Note that. The operating point may be set in a range obtained by appropriately dividing the operating region based on the target torque Tobj of the engine and the engine rotational speed Ne. Then, the process proceeds to step S70.

  In step S70, it is determined whether or not the number of ignition times Mign stored in step S60 is less than the predetermined number of consecutive times n that is less than the multiple ignition number Nign obtained in step S20. The predetermined number of consecutive times n is, for example, several times, and is set to an appropriate number in consideration of engine operation fluctuations and errors. If it is determined that the ignition number Mign is less than the multiple ignition number Nign for a predetermined consecutive number n, the process proceeds to step S80. If it is determined that the ignition number Mign is not less than the predetermined number of consecutive times n less than the multiple ignition number Nign, this routine is returned.

  In step S80, the number of times of ignition Nign at the operating point when it is determined in step S70 that the number of ignition times Mign is less than the number of times of multiple ignition Nign has been continued for a predetermined number of times n. rewrite. That is, in the map as shown in FIG. 3, the multiple ignition number Nign in the multiple ignition region inside the broken line is rewritten. This step corresponds to the control in the learning control unit 16 of the present invention. Then, this routine ends.

In step S90, ignition is performed once. One-time ignition is fixed ignition in which ignition is performed once (predetermined number of times) in one cycle. Then, the process proceeds to step S100.
In step S100, the ignition determination of the cylinder that has been ignited once in step S90 is not performed. Then, this routine ends.
As described above, the engine according to the first embodiment of the present invention includes the multiple ignition system that performs the number of times of ignition in one cycle a plurality of times. Furthermore, it is possible to switch the number of times of multiple ignition Nign, which is the number of times of ignition, from 2 to 5 times, and it is also possible to ignite only once. The multiple ignition number Nign is set based on engine operating points such as the engine speed Ne and the target torque Tobj. Furthermore, the engine control unit 10 performs ignition determination when performing multiple ignition, and determines how many ignitions have been performed.

  The engine control unit 10 determines that the number of times of ignition at the engine operating point is continued n times when the ignition number Mign determined to be ignited is n times less than the number of times of multiple ignition Nign set based on the engine operating point. The map is rewritten so as to be less than Nign stored once. Therefore, when ignition is performed at a number smaller than the number of multiple ignitions Nign set based on the engine operating point, the number of multiple ignitions Nign is set to be smaller by one. As a result, ignition after ignition is suppressed, and consumption of the electrode of the spark plug 2 is suppressed. Therefore, in the present embodiment, it is possible to protect the spark plug 2 by suppressing useless ignition after ignition while securing ignition performance by the multiple ignition system.

In particular, when the ignition number Mign determined to be ignited is smaller than the multiple ignition number Nign stored in the map, learning control is performed to rewrite the multiple ignition number Nign. It can be set to a small amount, and useless ignition can be further suppressed.
Next, the ignition frequency control procedure of the second embodiment will be described with reference to FIG. Hereinafter, only different points from the control shown in FIG. 2 of the first embodiment will be described.

As shown in FIG. 5, the ignition frequency control of the second embodiment proceeds from step S60 to step S110.
In step S110, it is determined whether or not the ignition frequency Mign stored in step S60 is 1 for the predetermined continuous frequency m. The predetermined number of consecutive times m is, for example, several times as with the predetermined number of consecutive times n, and is set to an appropriate number in consideration of engine operation fluctuations and errors. If the number of ignition times Mign is 1 for the predetermined number of consecutive times m, the process proceeds to step S120. If the number of ignition times Mign is not 1, the routine is returned.

In step S120, the multiple ignition count Nign at the operating point when it is determined in step S110 that the ignition count Mign is 1 for a predetermined continuous count m times is rewritten to 1. That is, in the map as shown in FIG. 3, the broken line that is the boundary line between multiple ignition and single ignition is rewritten. Then, this routine ends.
As described above, in the second embodiment of the present invention, when the number of ignition times Mign determined to be ignited is m times, the multiple ignition number Nign at that engine operating point is set to 1. rewrite. Therefore, in the present embodiment, the control for changing the region for switching between the multiple ignition and the single ignition is performed, and the control for performing the multiple ignition despite the ignition by the single ignition is suppressed. The consumption of the electrode of the plug 2 can be suppressed.

  Further, the ignition frequency control that suppresses the ignition frequency by the ignition determination in the above embodiment may be performed only in a region (predetermined operation region) in which the in-cylinder flow is equal to or greater than a predetermined value. For example, in an engine having a lean burn or EGR introduction mechanism, the air / fuel ratio of the air-fuel mixture (ratio of the amount of fuel mixed with the amount of air) is calculated from the theoretical mixture ratio in order to improve fuel efficiency at low rotation and low load. However, there is a control in which the flow in the cylinder is increased to improve the combustibility in this region. Thus, in the region where the air-fuel ratio is thin and the EGR is large, the air-fuel mixture is difficult to ignite, and in the region where the in-cylinder flow is large, the spark between the electrodes of the spark plug 2 flows and it is difficult to ignite. In order to ignite, the multiple ignition number Nign is set to a large number in advance in the map. Therefore, in the region where the number of ignitions is set to be large, the number of times of multiple ignition Nign can be effectively reduced while ensuring ignition by performing the suppression control of the number of ignitions by the ignition determination as in the present embodiment. it can.

  Moreover, in the above embodiment, as shown in FIG. 3, it is set to one-time ignition in a high rotation or high load region. As described above, in the high rotation or high load region, the control is adopted in which the air-fuel ratio of the air-fuel mixture is higher than the stoichiometric mixture ratio or the stoichiometric mixture ratio or introduced with a small amount of EGR. Since it is also a state, it is easy to ignite. In such a high temperature region where ignition is easy, by fixing to one ignition, it is possible to reduce the control load without performing the ignition determination and the number of ignition times control. In the above embodiment, the number of multiple ignitions Nign is set to 2 to 5 times, but may be set to exceed 5 times.

Further, when the ignition number Mign obtained by the ignition determination is n times or less than the multiple ignition number Nign, the learning control is performed to reduce the number of ignitions. Therefore, it is possible to suppress an excessive decrease in the number of ignitions due to engine operation fluctuations and errors, and to suppress a decrease in ignition performance due to a decrease in the number of ignitions.
The number of times of multiple ignition Nign is not set as it is as the number of times of multiple ignition Nign set by the ignition determination, but may be set several times (predetermined times). Thereby, ignition can be performed reliably and the output performance of the engine can be ensured.

  In addition, about the said 1st Embodiment and 2nd Embodiment, it is sufficient to perform only one, However, If it performs both, a useless ignition can be suppressed. In the above embodiment, only the learning control for decreasing the number of ignitions is performed when the number of ignitions Mign obtained by the ignition determination is less than the number of multiple ignitions Nign for a predetermined number of times. When the ignition determination is not made during the number of times of heavy ignition Nign (in the case of misfire), it is better to perform control to increase the number of ignitions from the next cycle. Further, the ignition determination may be performed even in the region where the single ignition is performed, and when the ignition determination is not made (when a misfire has occurred), multiple ignition may be performed from the next cycle.

The present invention is not limited to the above embodiment. For example, the map for setting the number of times of multiple ignition Nign may be changed as appropriate according to the structure, type, etc. of the engine. For example, the map may be set according to the engine speed, the air-fuel ratio, and the EGR introduction ratio. With regard to the multiple ignition number Nign, the ignition after the ignition determination may be restricted without performing learning control.
In the above embodiment, the number of ignitions can be suppressed from the next cycle by rewriting the multiple ignition number Nign set based on the engine operating point based on the ignition number Mign determined to be ignited. The subsequent ignition in the cycle determined to be ignited may be suppressed. Specifically, the ignition may be performed until the ignition number Mign determined to be ignited (because Mign + 1 is prepared for ignition when the ignition is performed for the Mign number of times), and the ignition in the cycle may be terminated. By controlling in this way, ignition after ignition can be suppressed and consumption of the electrode of the spark plug 2 can be suppressed.

  The present invention can be widely applied to an internal combustion engine capable of igniting a plurality of times in one cycle, such as an engine equipped with a multiple ignition system.

1 Ignition device 2 Spark plug (igniter)
DESCRIPTION OF SYMBOLS 10 Engine control unit 13 Ignition frequency setting part 14 Ignition determination part 15 Ignition control part 16 Learning control part

Claims (6)

Provided in an internal combustion engine having a multiple ignition system that ignites a plurality of times with one spark plug in one cycle,
An ignition number setting unit for setting the number of ignitions in one cycle based on the operating state of the internal combustion engine;
An ignition determination unit for determining ignition in a cylinder of the internal combustion engine;
An ignition control unit that suppresses the number of subsequent ignitions based on the number of ignitions when the ignition determination unit determines ignition; and
An ignition device for an internal combustion engine, comprising:   2. The internal combustion engine according to claim 1, wherein the ignition control unit executes suppression of the number of times of ignition when the ignition determination is made in a predetermined operation region where the in-cylinder flow of the internal combustion engine is equal to or greater than a predetermined value. Engine ignition device.   The ignition number setting unit is a multiple ignition that suppresses the number of ignitions in one cycle based on the ignition determination based on the operating state of the internal combustion engine, and a fixed that is fixed to a predetermined number without performing the ignition determination. The ignition device for an internal combustion engine according to claim 1, wherein the ignition device is switched to ignition.   4. The ignition device for an internal combustion engine according to claim 3, wherein the ignition frequency setting unit fixes the ignition frequency to the predetermined number in an operating state where the inside of the cylinder is in a predetermined high temperature region. 5.   5. The ignition device for an internal combustion engine according to claim 1, wherein the ignition control unit suppresses the ignition after performing the ignition determination and igniting a predetermined number of times. 6.   A learning control unit is provided that performs learning control for reflecting the number of ignitions when the ignition determination unit determines the ignition in the ignition number setting unit set in the ignition number setting unit in the next and subsequent cycles. The ignition device for an internal combustion engine according to any one of claims 1 to 5.

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