JP7743371B2 - Internal combustion engine control device and internal combustion engine control method - Google Patents

Description

The present invention relates to an internal combustion engine control device and an internal combustion engine control method.

In recent years, there has been an increasing demand for improved fuel efficiency in gasoline engines used in automobiles. As a result, the adoption of ultra-high EGR and ultra-lean burn in internal combustion engines is being considered. In this case, ignition control is required to ensure the ignition of the mixture. Furthermore, it is necessary to improve lean tolerance so that lean mixtures can be ignited stably. One effective means of achieving this is pre-ignition, which heats up the spark plug installed in the combustion chamber in advance. Pre-ignition is performed at a time when the fuel will not be ignited.

Pre-ignition technology is described, for example, in Patent Document 1. Patent Document 1 discloses an ignition device for an internal combustion engine and a vehicle control device that performs pre-ignition by performing multiple discharges in the spark plug from the exhaust stroke to the intake stroke as ignition control for lean burn. The internal combustion engine ignition device disclosed in Patent Document 1 ends pre-ignition before the main ignition that burns the air-fuel mixture and before outputting a fuel injection signal.

International Publication No. 2019/087748

However, the vehicle control device described in Patent Document 1 generates a large amount of discharge at the electrodes of the spark plug, which accelerates electrode wear and shortens the lifespan of the electrodes. Furthermore, the increased energy input to the ignition coil causes the ignition coil to heat up, which could damage the ignition device or shorten its lifespan.

In view of the above problems, the present invention aims to provide an internal combustion engine control device and an internal combustion engine control method that can reduce misfires during lean burn by implementing pre-ignition and suppress deterioration of the ignition device.

To solve the above problems and achieve the present object, an internal combustion engine control device of the present invention controls an internal combustion engine including a combustion chamber and an ignition device that generates a spark to ignite the air-fuel mixture in the combustion chamber. The internal combustion engine control device includes a control unit that controls the ignition device during the intake stroke of the combustion cycle of the internal combustion engine to perform pre-ignition that is different from the main ignition for igniting the air-fuel mixture. The control unit determines the ignition period and frequency of a pre-ignition signal to be output to the ignition device according to the flow state of the air-fuel mixture in the combustion chamber. The control unit divides the intake stroke into a high-flow-velocity section where the flow velocity of the air-fuel mixture is equal to or greater than a predetermined value and a low-flow-velocity section where the flow velocity of the air-fuel mixture is less than the predetermined value, and performs the pre-ignition preferentially in the high-flow-velocity section and changes the ignition period and frequency of the pre-ignition performed in the high-flow-velocity section.

This invention reduces misfires during lean burn and suppresses deterioration of the ignition device.

1 is a diagram showing an example of a basic configuration of an internal combustion engine according to a first embodiment; 1 is a functional block diagram illustrating a functional configuration of an internal combustion engine control device according to a first embodiment. 5 is a diagram showing a change over time in the flow velocity of the air-fuel mixture around the spark plug according to the first embodiment and a pre-ignition signal. FIG. FIG. 10 is a functional block diagram illustrating the functional configuration of an internal combustion engine control device according to a second embodiment. FIG. 10 is a functional block diagram illustrating the functional configuration of an internal combustion engine control device according to a third embodiment. FIG. 11 is a diagram showing the relationship between the flow velocity of the air-fuel mixture and the intake valve lift according to the third embodiment. FIG. 10 is a functional block diagram illustrating the functional configuration of an internal combustion engine control device according to a fourth embodiment. FIG. 11 is a functional block diagram illustrating the functional configuration of an internal combustion engine control device according to a fifth embodiment.

The following describes an internal combustion engine control device according to an embodiment. Note that common components in each figure are assigned the same reference numerals.

First Embodiment
[Configuration of internal combustion engine]
First, the configuration of the internal combustion engine according to the first embodiment will be described.
FIG. 1 is an overall configuration diagram showing an example of the basic configuration of an internal combustion engine according to a first embodiment of the present invention.

The internal combustion engine 1 shown in Figure 1 may have a single cylinder or multiple cylinders, but in this embodiment, an internal combustion engine 1 having four cylinders will be described as an example.

As shown in FIG. 1, the internal combustion engine 1 includes a piston 101, a cylinder 102, and a cylinder head 103. A crankshaft 105 is connected to the piston 101 via a connecting rod 104. The cylinder head 103, the crown surface 101P of the piston 101, and the inner wall 102a of the cylinder 102 form a combustion chamber 106.

An ignition device 110 is located directly above the combustion chamber 106. The ignition device 110 has an ignition plug 111 and an ignition coil 112. The ignition plug 111 has an electrode 113. The electrode 113 generates a spark to ignite the air-fuel mixture M.

The combustion chamber 106 is connected to an intake port 121 and an exhaust port 122. An intake valve 123 is provided between the combustion chamber 106 and the intake port 121. The intake valve 123 opens and closes the intake port 121 side of the combustion chamber 106. An exhaust valve 124 is provided in the exhaust port 122. The exhaust valve 124 opens and closes the exhaust port 122 side of the combustion chamber 106.

When the intake valve 123 opens during the intake stroke, the air-fuel mixture M flows from the intake port 121 into the combustion chamber 106. The air-fuel mixture M is then compressed by the piston 101. Then, when a main ignition signal is sent to the ignition coil 112 at the appropriate time, the electrode 113 of the spark plug 111 generates a spark.

When a spark is generated by the electrode 113, the air-fuel mixture M in the combustion chamber 106 is ignited, causing the mixture M in the combustion chamber 106 to burn. This increases the pressure in the combustion chamber 106, pushing the piston 101 down. As a result, the connecting rod 104 is displaced, causing the crankshaft 105 to rotate.

In recent years, lean burn, in which the fuel content of the air-fuel mixture M is reduced, has been adopted to reduce carbon dioxide emissions generated during fuel combustion in internal combustion engines. With lean burn, when the internal combustion engine 1 is started cold or when the temperature of the internal combustion engine 1 has not yet risen sufficiently, poor ignition of the air-fuel mixture M can occur, resulting in a misfire in which the flame goes out mid-combustion.

When a misfire occurs, the combustion speed decreases, generating hydrocarbons, which increases hydrocarbon emissions. Therefore, when implementing lean burn, measures to improve combustion are required when starting the internal combustion engine 1 or when the temperature is low. Therefore, in this embodiment, a pre-ignition is performed to raise the temperature of the spark plug 111 before performing the main ignition, thereby improving the combustibility of the air-fuel mixture M.

[Configuration of the internal combustion engine control device]
Next, the configuration of the internal combustion engine control device according to the first embodiment will be described with reference to FIG.
FIG. 2 is a functional block diagram illustrating the functional configuration of the internal combustion engine control device according to the first embodiment.

The internal combustion engine control device 201 (hereinafter referred to as "control device 201") shown in FIG. 2 is, for example, an engine control unit (ECU). The control device 201 has a flow velocity estimation unit 202 and a preliminary ignition signal calculation unit 203. The flow velocity estimation unit 202 and the preliminary ignition signal calculation unit 203 correspond to the control unit according to the present invention.

The flow velocity estimation unit 202 estimates the flow velocity of the air-fuel mixture M around the spark plug 111. Various information necessary to estimate the flow velocity of the air-fuel mixture M around the spark plug 111 is input to the flow velocity estimation unit 202. The various information is detected or measured by the sensor group 204. The various information includes the intake air amount, crank angle, secondary voltage of the ignition coil 112, valve profile, rotation speed of the internal combustion engine 1, intake pressure, coolant temperature, etc.

The intake air volume is the amount of air flowing into the combustion chamber 106. The intake air volume is measured by an air flow sensor installed in the intake port 121. The crank angle is the rotation angle of the crankshaft 105. The crank angle is detected by a crank angle sensor. The crank angle sensor is installed radially outside a ring gear (not shown) attached to the crankshaft 105.

The secondary voltage of the ignition coil 112 is detected by a voltmeter provided in the electrical circuit of the ignition device 110. The valve profile is data indicating the lift amount of the intake valve 123 according to the crank angle. The intake pressure is the pressure of the gas in the intake port 121. The intake pressure is detected by a pressure sensor provided in the intake port 121. The coolant temperature is the temperature of the coolant in the internal combustion engine 1. The coolant temperature is measured by a water temperature sensor. The water temperature sensor is provided in the water jacket (not shown) of the cylinder head 103.

The information input to the flow velocity estimation unit 202 may include information about the combustion state in the previous combustion cycle and the flow state of the mixture M around the spark plug 111 during the intake stroke. The flow velocity estimation unit 202 may also estimate the flow velocity of the mixture M around the spark plug 111 based on a map created from numerical calculations or experimental results performed in advance. The control device 201 may also create learning results or a map that associates operating conditions with estimated values for the flow velocity of the mixture M from past operating data of the internal combustion engine 1.

The preliminary ignition signal calculation unit 203 calculates the duration of preliminary ignition, the start timing of preliminary ignition, the period of preliminary ignition (hereinafter referred to as the "ignition period"), the number of preliminary ignitions (hereinafter referred to as the "number of ignitions"), the electrical energy used for preliminary ignition, etc., based on the flow velocity of the air-fuel mixture M around the spark plug 111 estimated by the flow velocity estimation unit 202. For example, when the flow velocity of the air-fuel mixture M around the spark plug is high, the preliminary ignition signal calculation unit 203 shortens the period of preliminary ignition and reduces the electrical energy used for preliminary ignition.

The preliminary ignition signal calculation unit 203 generates a preliminary ignition signal (see Figure 3) that repeatedly turns ON and OFF depending on the calculated preliminary ignition implementation period, start timing, ignition period, number of ignitions, electrical energy, etc. For example, if the preliminary ignition period is to be shortened, the period of the preliminary ignition signal is shortened. Also, if the electrical energy used for preliminary ignition is to be reduced, the number of times the preliminary ignition signal is turned ON (number of ignitions) is reduced or the frequency of the preliminary ignition signal is increased.

The preliminary ignition signal calculation unit 203 outputs the generated preliminary ignition signal to the ignition coil 112. This applies a high voltage to the electrode 113 of the spark plug 111, and multiple discharges (preliminary ignitions) are performed in response to the preliminary ignition signal.

When a high voltage is applied to the electrode 113 of the spark plug 111, chemical species such as ozone are generated in the air-fuel mixture M. Ozone contributes to combustion stability. Therefore, when the ozone generated by applying a high voltage to the electrode 113 is distributed approximately evenly within the combustion chamber 106, combustion stability during lean burn is improved. As a result, misfires that occur during combustion and the generation of hydrocarbons that accompany misfires can be suppressed.

Ozone and other chemical species generated by applying a high voltage to the electrode 113 can be diffused throughout the combustion chamber 106 by being carried by the flow of the air-fuel mixture M around the spark plug 111. In this embodiment, a pre-ignition signal is generated with an ignition period and frequency (electrical energy used) that correspond to the timing at which the chemical species such as ozone can be favorably diffused and the flow speed of the air-fuel mixture M at that time. This reduces the number of pre-ignitions and the electrical energy required for pre-ignition.

[Backup ignition signal]
Next, the pre-ignition signal according to the flow state of the air-fuel mixture M will be described with reference to FIG.
FIG. 3 is a diagram showing the flow velocity of the air-fuel mixture M around the spark plug 111 and the change over time in the pre-ignition signal.

As shown in Figure 3, during the intake stroke 301, the flow of the air-fuel mixture M around the spark plug 111 is not constant but constantly fluctuates. In particular, in HEV (Hybrid Electric Vehicle) vehicles, the motoring speed at startup is faster than in vehicles equipped with only an internal combustion engine, so fluctuations in flow velocity during the intake stroke are more pronounced.

The intake stroke 301 is composed of a high flow velocity section 302 and a low flow velocity section 303. The high flow velocity section 302 may be defined, for example, as a section in which the flow velocity of the air-fuel mixture M around the spark plug 111 during the intake stroke 301 is equal to or greater than the average value 310.

In the high flow velocity section 302, the flow velocity of the mixture M is relatively high. Therefore, in the high flow velocity section 302, chemical species such as ozone generated by the discharge of the pre-ignition can be more effectively diffused into the combustion chamber 106.

On the other hand, in the low flow rate section 303, the flow velocity of the mixture M is relatively low. Therefore, in the low flow rate section 303, chemical species such as ozone are less likely to diffuse into the combustion chamber 106. As a result, pre-ignition in the low flow rate section 303 does not improve the combustibility of the combustion chamber 106 as a whole, and its effect is limited.

Furthermore, since the low flow rate section 303 is often in the latter half of the intake stroke 301, fuel may have already reached the spark plug 111. If pre-ignition is performed in this case, the lean mixture around the spark plug 111 may ignite, generating hydrocarbons. This could result in poor exhaust quality.

Furthermore, in the low flow rate section 303, chemical species such as ozone generated by the discharge of the pre-ignition performed in the high flow rate section 302 may be carried by the flow of the air-fuel mixture M and return to the area around the spark plug 111. If a discharge occurs there, chemical species such as ozone may change into other chemical species, which could reduce the effectiveness of the pre-ignition.

It is therefore desirable to generate a preliminary ignition signal 304 that prioritizes preliminary ignition in the high flow velocity section 302. Note that in the low flow velocity section 303, a preliminary ignition signal 305 may be generated that causes the number of ignitions and the total amount of electrical energy to be less than the number of ignitions and the total amount of electrical energy in the high flow velocity section 302.

Furthermore, when a preliminary ignition signal is output from the high flow velocity section 302 to the low flow velocity section 303, a preliminary ignition signal 306 may be generated that reduces the number of ignitions depending on the flow velocity of the mixture M, the elapsed crank angle, etc.

By the way, if the frequency (pulse width) and ignition period are changed according to the predicted flow speed of the air-fuel mixture M, re-discharge due to the extension of the discharge path will not occur, and pre-ignition will be stable. Therefore, a pre-ignition signal 307 may be generated whose frequency and ignition period are changed according to the flow speed of the air-fuel mixture M.

Preferentially performing pre-ignition in the high flow rate section 302 reduces the number of ignitions and the amount of electrical energy used compared to performing pre-ignition throughout the entire intake stroke 301. This reduces wear on the electrode 113 of the spark plug 111 and prevents the ignition coil 112 from becoming too hot. As a result, deterioration of the ignition device 110 can be suppressed. Furthermore, chemical species such as ozone are efficiently distributed throughout the combustion chamber 106, improving combustibility during main ignition.

Second Embodiment
[Configuration of the internal combustion engine control device]
Next, the configuration of an internal combustion engine control device according to a second embodiment will be described with reference to Fig. 4. The internal combustion engine according to the second embodiment is the same as the internal combustion engine 1 according to the first embodiment.
FIG. 4 is a functional block diagram illustrating the functional configuration of the internal combustion engine control device according to the second embodiment.

The internal combustion engine control device 401 (hereinafter referred to as "control device 401") shown in FIG. 4 is, for example, an engine control unit (ECU). The control device 401 has a flow velocity estimation unit 402 and a preliminary ignition signal calculation unit 403. The flow velocity estimation unit 402 and the preliminary ignition signal calculation unit 403 correspond to the control unit according to the present invention.

The flow velocity estimation unit 402 has a discharge path length calculation unit 421 and a flow velocity calculation unit 422. The discharge path length calculation unit 421 receives the secondary voltage (secondary voltage history 404) of the ignition coil 112 during the preliminary ignition performed in the previous combustion cycle. The control device 401 has a memory unit (not shown) that stores the secondary voltage history 404.

The discharge path length calculation unit 421 calculates the length of the discharge path formed at the electrode 113 of the spark plug 111 from the input secondary voltage history 404. The discharge path length calculation unit 421 calculates the length of the discharge path using an equation that associates the secondary voltage value with the discharge path length. The discharge path length calculation unit 421 outputs the calculated discharge path length estimate value to the flow velocity calculation unit 422.

The flow velocity calculation unit 422 calculates the flow velocity of the mixture M around the spark plug 111 in the previous combustion cycle from the discharge path length estimate. The flow velocity calculation unit 422 calculates the flow velocity of the mixture M using an equation that relates the length of the discharge path to the flow velocity of the mixture M around the spark plug 111. The flow velocity calculation unit 422 outputs the calculation result (flow velocity) to the preliminary ignition signal calculation unit 403.

The preliminary ignition signal calculation unit 403 has a flow velocity section determination unit 431 and a preliminary ignition signal generation unit 432. The flow velocity section determination unit 431 divides the intake stroke 301 into a high flow velocity section 302 and a low flow velocity section 303 based on the flow velocity of the air-fuel mixture M around the spark plug 111. The preliminary ignition signal calculation unit 403 outputs the high flow velocity section 302 and the low flow velocity section 303 to the preliminary ignition signal generation unit 432.

The preliminary ignition signal generation unit 432 calculates the duration, start timing, ignition period, number of ignitions, electrical energy, etc. of preliminary ignition based on the high flow velocity section 302 and the low flow velocity section 303. At this time, the preliminary ignition signal generation unit 432 may calculate the ignition period, number of ignitions, electrical energy, etc., taking into account the flow speed of the air-fuel mixture M around the ignition plug 111.

The preliminary ignition signal generation unit 432 generates a preliminary ignition signal according to the duration, start timing, ignition cycle, number of ignitions, electrical energy, etc. of the preliminary ignition. The preliminary ignition signal generation unit 432 then outputs the generated preliminary ignition signal to the ignition coil 112. As a result, a high voltage is applied to the electrode 113 of the spark plug 111, and multiple discharges (preliminary ignitions) are performed according to the preliminary ignition signal.

In this way, in the second embodiment, the flow velocity of the air-fuel mixture M around the spark plug 111 in the previous combustion cycle is fed back to estimate the flow velocity of the air-fuel mixture M around the spark plug 111 in the current combustion cycle. Furthermore, a high flow velocity section 302 is detected from the flow velocity of the air-fuel mixture M, and a pre-ignition signal for performing pre-ignition in the high flow velocity section 302 is generated (see pre-ignition signal 304 in Figure 3).

This reduces the number of ignitions and the amount of electrical energy used compared to when pre-ignition is performed throughout the entire intake stroke 301. This also reduces wear on the electrode 113 of the spark plug 111 and prevents the ignition coil 112 from becoming too hot. As a result, deterioration of the ignition device 110 can be suppressed. Furthermore, because chemical species such as ozone are efficiently distributed throughout the combustion chamber 106, combustibility during main ignition can be improved.

Third Embodiment
[Configuration of the internal combustion engine control device]
Next, the configuration of an internal combustion engine control device according to a third embodiment will be described with reference to Figures 5 and 6. The internal combustion engine according to the third embodiment is the same as the internal combustion engine 1 according to the first embodiment.
Fig. 5 is a functional block diagram illustrating the functional configuration of an internal combustion engine control device according to the third embodiment. Fig. 6 is a diagram illustrating the relationship between the flow velocity of the air-fuel mixture and the intake valve lift according to the third embodiment.

The internal combustion engine control device 501 (hereinafter referred to as "control device 501") shown in FIG. 5 is, for example, an engine control unit (ECU). The control device 501 has a flow velocity estimation unit 502 and a preliminary ignition signal calculation unit 403. The preliminary ignition signal calculation unit 403 is the same as in the second embodiment. The flow velocity estimation unit 502 and the preliminary ignition signal calculation unit 403 correspond to the control unit according to the present invention.

The flow velocity estimation unit 502 receives inputs of a valve profile 504, a crank angle 505, an engine speed 506, and an intake pressure 507. The internal combustion engine system according to the third embodiment includes a rotation speed measurement unit (not shown) that measures the engine speed 506 of the internal combustion engine 1, and a pressure sensor (not shown) that detects the intake pressure 507.

The internal combustion engine system according to the third embodiment also includes a valve timing control unit 508 that updates the valve profile 504, and a crank angle sensor 509 that detects the crank angle 505. The valve timing control unit 508, as represented by a variable timing camshaft (VTC) mechanism, changes the opening and closing timing of the intake valve 123. The valve timing control unit 508 updates the valve profile 504 when the opening and closing timing of the intake valve 123 is changed.

The flow velocity estimation unit 502 has a valve lift calculation unit 521 and a flow velocity calculation unit 522. The valve lift calculation unit 521 receives the valve profile 504 and the crank angle 505. The valve lift calculation unit 521 calculates the valve lift amount of the intake valve 123 relative to the crank angle 505 based on the valve profile 504 and the crank angle 505. The valve lift calculation unit 521 outputs the calculated valve lift amount to the flow velocity calculation unit 522.

The flow velocity calculation unit 522 calculates the flow velocity of the air-fuel mixture M around the spark plug 111 from the valve lift amount, rotation speed 506, and intake pressure 507. The flow velocity calculation unit 522 outputs the calculated flow velocity of the air-fuel mixture M to the preliminary ignition signal calculation unit 403. The processing of the flow velocity section determination unit 431 and preliminary ignition signal generation unit 432 of the preliminary ignition signal calculation unit 403 is the same as in the second embodiment, so a description thereof will be omitted.

In the third embodiment, preliminary ignition is also performed preferentially in the high flow rate section 302. This reduces the number of ignitions and the electrical energy used compared to when preliminary ignition is performed throughout the entire intake stroke 301. This also reduces wear on the electrode 113 of the spark plug 111 and prevents the ignition coil 112 from becoming too hot. As a result, deterioration of the ignition device 110 can be suppressed. Furthermore, chemical species such as ozone are efficiently distributed throughout the combustion chamber 106, improving combustibility during main ignition.

At the time when the intake valve 123 begins to open, as shown in Figure 6, the difference between the intake pressure 507 and the pressure inside the combustion chamber 106 is large, so a large amount of mixture M flows into the combustion chamber 106, or the mixture M flows back toward the cylinder head 103. At this time, the flow of mixture M inside the combustion chamber 106, including around the spark plug 111, becomes stronger. Therefore, the flow speed of mixture M around the spark plug 111 increases.

On the other hand, when the intake valve 123 finishes opening, the pressure inside the combustion chamber 106 and the intake pressure become close to each other, so the flow of gas into the combustion chamber 106 becomes slower. This weakens the flow of the air-fuel mixture M inside the combustion chamber 106, including around the spark plug 111. Therefore, the flow speed of the air-fuel mixture M around the spark plug 111 becomes slower.

Therefore, the flow velocity section determination unit 431 may determine the period from the crank angle at which the intake valve 123 starts to open to the crank angle at which the intake valve 123 finishes fully opening as the high flow velocity section 302. In this case, a crank angle calculation unit is provided that calculates the crank angle at which the intake valve 123 starts to open and the crank angle at which the intake valve 123 is fully open from the valve lift amount calculated by the valve lift calculation unit 521. This allows the flow velocity section determination unit 431 to easily determine the high flow velocity section 302.

Fourth Embodiment
[Configuration of the internal combustion engine control device]
Next, the configuration of an internal combustion engine control device according to a fourth embodiment will be described with reference to Fig. 7. The internal combustion engine according to the fourth embodiment is the same as the internal combustion engine 1 according to the first embodiment.
FIG. 7 is a functional block diagram illustrating the functional configuration of an internal combustion engine control device according to the fourth embodiment.

The internal combustion engine control device 601 (hereinafter referred to as "control device 601") shown in FIG. 7 is, for example, an engine control unit (ECU). The control device 601 has a flow velocity estimation unit 602 and a preliminary ignition signal calculation unit 403. The preliminary ignition signal calculation unit 403 is the same as in the second embodiment. The flow velocity estimation unit 602 and the preliminary ignition signal calculation unit 403 correspond to the control unit according to the present invention.

The flow velocity estimation unit 602 receives a flow velocity map 604 and operating conditions 605 of the internal combustion engine 1. The operating conditions 605 include, for example, the rotation speed of the internal combustion engine 1, intake pressure, throttle opening, coolant temperature, intake air volume, fuel injection volume, and crank angle.

The internal combustion engine system according to the fourth embodiment includes a map update unit 611 that updates the flow velocity map 604 in accordance with the operation of the internal combustion engine 1, and an operating condition acquisition unit 612 that acquires the operating conditions 605. Examples of the operating condition acquisition unit 612 include a throttle opening sensor that detects the throttle opening, and a fuel flow meter that measures the fuel injection amount.

The flow velocity map 604 associates preset operating conditions 605 with the flow velocity of the air-fuel mixture M around the spark plug 111. The flow velocity map 604 is obtained, for example, by three-dimensional fluid simulation, to show the change over time in the flow velocity of the air-fuel mixture M around the spark plug 111 for the operating conditions 605. The flow velocity map 604 may also define the high flow velocity section 302 for the operating conditions 605.

The flow velocity estimation unit 602 has a map storage unit 621, a map selection unit 622, and a flow velocity calculation unit 623. The map storage unit 621 stores (stores) the multiple flow velocity maps 604 that are supplied. The map selection unit 622 selects a flow velocity map 604 that corresponds to the operating conditions 605 at that time from the multiple flow velocity maps 604 stored in the map storage unit 621.

The flow velocity calculation unit 623 determines the flow velocity of the mixture M around the spark plug 111 from the flow velocity map 604 selected by the map selection unit 622. The flow velocity calculation unit 623 outputs the determined flow velocity of the mixture M around the spark plug 111 to the preliminary ignition signal calculation unit 403. The processing of the flow velocity zone determination unit 431 and preliminary ignition signal generation unit 432 of the preliminary ignition signal calculation unit 403 is the same as in the second embodiment, so description thereof will be omitted.

In the fourth embodiment, pre-ignition is also performed preferentially in the high flow rate section 302. This reduces the number of ignitions and the electrical energy used compared to when pre-ignition is performed throughout the entire intake stroke 301. This also reduces wear on the electrode 113 of the spark plug 111 and prevents the ignition coil 112 from becoming too hot. As a result, deterioration of the ignition device 110 can be suppressed. Furthermore, because chemical species such as ozone are efficiently distributed within the combustion chamber 106, the combustibility of the mixture M during main ignition can be improved.

Fifth Embodiment
[Configuration of the internal combustion engine control device]
Next, the configuration of an internal combustion engine control device according to a fifth embodiment will be described with reference to Fig. 8. Note that the multiple internal combustion engines according to the fifth embodiment are the same as the internal combustion engine 1 according to the first embodiment.
FIG. 8 is a functional block diagram illustrating the functional configuration of an internal combustion engine control device according to the fifth embodiment.

As shown in FIG. 8, the internal combustion engine system according to the fifth embodiment includes multiple internal combustion engines 1A, 1B, ..., 1X. Each of the multiple internal combustion engines 1A, 1B, ..., 1X has an ignition plug 111A, 111B, ..., 111X and an ignition coil 112A, 112B, ..., 112X.

The internal combustion engine control device 701 (hereinafter referred to as "control device 701") shown in FIG. 8 is, for example, an engine control unit (ECU). The control device 701 has a flow velocity estimation unit 702 and a preliminary ignition signal calculation unit 703. The flow velocity estimation unit 702 and the preliminary ignition signal calculation unit 703 correspond to the control unit according to the present invention.

The flow velocity estimation unit 702 estimates the flow velocity of the air-fuel mixture M around each spark plug 111A, 111B, ... 111X. Various information necessary to estimate the flow velocity of the air-fuel mixture M around each spark plug 111A, 111B, ... 111X is input to the flow velocity estimation unit 702. The various information is detected or measured by the sensor group 704. The various information includes the intake air amount, crank angle, secondary voltage of the ignition coils 112A, 112B, ... 112X, valve profile, engine speed, intake pressure, and coolant temperature for each internal combustion engine 1A, 1B, ... 1X.

The preliminary ignition signal calculation unit 703 calculates the preliminary ignition duration, start timing, ignition cycle, number of ignitions, electrical energy, etc. for each ignition device based on the flow speed of the air-fuel mixture M around each spark plug 111A, 111B, ... 111X. The preliminary ignition signal calculation unit 703 then generates a preliminary ignition signal for each ignition device based on the calculated preliminary ignition duration, start timing, ignition cycle, number of ignitions, electrical energy, etc.

The preliminary ignition signal calculation unit 703 outputs the generated preliminary ignition signal to the ignition coils 112A, 112B, ... 112X. This applies a high voltage to each electrode of the ignition plugs 111A, 111B, ... 111X, and multiple discharges (preliminary ignitions) are performed in response to the preliminary ignition signal.

The flow pattern of the mixer M in the combustion chamber of each internal combustion engine 1A, 1B, ... 1X is affected by factors such as valve timing, intake pressure fluctuations, and the orientation of the spark plugs 111A, 111B, ... 111X. As a result, the flow pattern of the mixer M in the combustion chamber of each internal combustion engine 1A, 1B, ... 1X differs from one another.

The preliminary ignition signal calculation unit 703 therefore determines the optimal preliminary ignition duration, start timing, ignition cycle, number of ignitions, electrical energy, etc., depending on the flow state of the mixer M in the combustion chamber of each internal combustion engine 1A, 1B...1X. The preliminary ignition signal calculation unit 703 then generates a preliminary ignition signal for each internal combustion engine 1A, 1B...1X. This makes it possible to reduce the number of misfires and the generation of hydrocarbons for each internal combustion engine 1A, 1B...1X.

In addition, the number of preliminary ignitions and the amount of electrical energy used can be reduced for each internal combustion engine 1A, 1B...1X. This can reduce electrode wear on each spark plug 111A, 111B...111X, and prevent the ignition coils 112A, 112B...112X from becoming too hot. As a result, deterioration of the ignition device of each internal combustion engine 1A, 1B...1X can be suppressed. Furthermore, because chemical species such as ozone are efficiently distributed throughout the combustion chambers of each internal combustion engine 1A, 1B...1X, the combustibility of the air-fuel mixture M during main ignition in each internal combustion engine 1A, 1B...1X can be improved.

<Summary>
The internal combustion engine control device 201 according to the first embodiment described above includes a flow velocity estimation unit 202 and a pre-ignition signal calculation unit 203 (control unit) that control the ignition device 110 during the intake stroke of the combustion cycle of the internal combustion engine 1 to perform pre-ignition that is different from the main ignition for igniting the air-fuel mixture M. The pre-ignition signal calculation unit 203 determines the ignition period and frequency of the pre-ignition signal to be output to the ignition device 110 in accordance with the flow state of the air-fuel mixture M in the combustion chamber 106.
This allows pre-ignition to be performed at a timing that allows chemical species such as ozone to be favorably diffused, depending on the flow state of the air-fuel mixture M in the combustion chamber 106. This reduces the number of pre-ignitions and the electrical energy required for them. This reduces wear on the electrode 113 of the spark plug 111 and prevents the ignition coil 112 from becoming too hot. As a result, deterioration of the ignition device 110 can be suppressed. Furthermore, because chemical species such as ozone are efficiently distributed throughout the combustion chamber 106, the combustibility of the air-fuel mixture M during main ignition can be improved.

The pre-ignition signal calculation unit 403 (control unit) according to the second embodiment divides the intake stroke 301 into a high flow velocity section 302 in which the flow velocity of the air-fuel mixture M is equal to or greater than a predetermined value, and a low flow velocity section 303 in which the flow velocity of the air-fuel mixture M is less than the predetermined value. The pre-ignition signal calculation unit 403 then performs pre-ignition preferentially in the high flow velocity section 302.
This makes it easy to determine the timing for preferentially performing pre-ignition, and by performing pre-ignition, chemical species such as ozone can be favorably diffused.

The preliminary ignition signal calculation unit 403 (control unit) according to the second embodiment described above sets the number of preliminary ignitions performed in the high flow velocity section 302 to be greater than the number of preliminary ignitions performed in the low flow velocity section 303.
This allows a large amount of discharge to be performed at a timing when chemical species such as ozone can be diffused well, and as a result, a large amount of chemical species such as ozone can be generated at a timing when chemical species such as ozone can be diffused well.

The preliminary ignition signal calculation unit 403 (control unit) according to the second embodiment described above makes the total amount of electrical energy used in preliminary ignition performed in the high flow velocity section 302 greater than the total amount of electrical energy used in preliminary ignition performed in the low flow velocity section 303.
This makes it possible to suppress the use of electrical energy at times other than when chemical species such as ozone can be diffused well, thereby enabling efficient use of electrical energy when pre-ignition is performed.

The flow velocity estimation unit 402 (control unit) according to the second embodiment described above estimates the flow state of the mixture M around the spark plug 111 in the combustion chamber 106 based on the value of the secondary voltage of the ignition coil 112 when current is applied to the spark plug 111.
This eliminates the need to provide a detection unit for detecting the flow state of the air-fuel mixture M within the combustion chamber 106. As a result, the flow velocity estimation unit 402 (control unit) can easily grasp the flow state of the air-fuel mixture M around the spark plug 111 within the combustion chamber 106 without changing the configuration of the internal combustion engine 1.

The flow velocity estimation unit 502 (control unit) according to the third embodiment described above estimates the flow state of the air-fuel mixture M in the combustion chamber 106 from the valve profile of the intake valve 123 .
This eliminates the need to provide a detection unit for detecting the flow state of the air-fuel mixture M within the combustion chamber 106. As a result, the flow velocity estimation unit 502 (control unit) can easily grasp the flow state of the air-fuel mixture M around the spark plug 111 within the combustion chamber 106 without changing the configuration of the internal combustion engine 1.

The flow velocity estimation unit 502 (control unit) according to the third embodiment described above sets the period from the start of valve opening to the end of valve opening in the valve profile of the intake valve 123 as a high flow velocity section 302 in which the flow velocity of the air-fuel mixture M is equal to or greater than a predetermined value. Then, the pre-ignition signal calculation unit 403 (control unit) performs pre-ignition preferentially in the high flow velocity section 302.
This makes it easy to determine the timing for preferentially performing pre-ignition, and by performing pre-ignition, chemical species such as ozone can be favorably diffused.

The flow velocity estimation unit 502 (control unit) according to the fourth embodiment described above uses a flow velocity map 604 (map) that associates the operating conditions 605 of the internal combustion engine 1 with the flow state of the mixture M in the combustion chamber 106 to estimate the flow state of the mixture M in the combustion chamber 106 that corresponds to the current operating conditions 605.
This eliminates the need to provide a detection unit for detecting the flow state of the air-fuel mixture M within the combustion chamber 106. As a result, the flow velocity estimation unit 502 (control unit) can easily grasp the flow state of the air-fuel mixture M around the spark plug 111 within the combustion chamber 106 without changing the configuration of the internal combustion engine 1.

A plurality of internal combustion engines according to the fifth embodiment are provided, and a pre-ignition signal calculation unit 703 (control unit) determines the ignition period and frequency of the pre-ignition signal to be output to each ignition device in accordance with the flow state of the air-fuel mixture M in each combustion chamber.
This reduces the number of misfires and the generation of hydrocarbons in each of the internal combustion engines 1A, 1B, ..., 1X. It also suppresses deterioration of the ignition device of each of the internal combustion engines 1A, 1B, ..., 1X. Furthermore, because chemical species such as ozone are efficiently distributed within the combustion chambers of each of the internal combustion engines 1A, 1B, ..., 1X, it is possible to improve the combustibility of the air-fuel mixture M at the time of main ignition in each of the internal combustion engines 1A, 1B, ..., 1X.

In the internal combustion engine control method according to this embodiment, a flow velocity estimation unit 202 and a pre-ignition signal calculation unit 203 (control unit) control the ignition device 110 during the intake stroke of the combustion cycle of the internal combustion engine 1 to perform pre-ignition that is different from main ignition for igniting the air-fuel mixture M. When performing pre-ignition, the flow velocity estimation unit 202 estimates the flow state of the air-fuel mixture M in the combustion chamber 106. Then, the pre-ignition signal calculation unit 203 determines the ignition period and frequency of the pre-ignition signal to be output to the ignition device 110 in accordance with the flow state.
This allows pre-ignition to be performed at a timing that allows chemical species such as ozone to be favorably diffused, depending on the flow state of the air-fuel mixture M in the combustion chamber 106. This reduces the number of pre-ignitions and the electrical energy required for them. This reduces wear on the electrode 113 of the spark plug 111 and prevents the ignition coil 112 from becoming too hot. As a result, deterioration of the ignition device 110 can be suppressed. Furthermore, because chemical species such as ozone are efficiently distributed throughout the combustion chamber 106, the combustibility of the air-fuel mixture M during main ignition can be improved.

The present invention is not limited to the embodiments described above and shown in the drawings, and various modifications are possible without departing from the spirit of the invention as set forth in the claims.

The above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the configurations described. It is also possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

1, 1A, 1B, 1X...Internal combustion engine, 101...Piston, 102...Cylinder, 103...Cylinder head, 104...Connecting rod, 105...Crankshaft, 106...Combustion chamber, 110...Ignition device, 111, 111A, 111B, 111X...Spark plug, 112, 112A, 112B, 112X...Ignition coil, 113...Electrode, 121...Intake port, 122...Exhaust port, 123...Intake valve, 124...Exhaust valve, 201, 401, 501, 601, 701...Control device (internal combustion engine control device), 202, 402, 502, 602, 702...Flow velocity estimation unit, 203, 403, 703...Preliminary ignition signal calculation unit, 204, 704...Sensor group, 301...Intake stroke, 302...High flow velocity section, 303...Low flow velocity section, 304, 305, 306, 307...Preliminary ignition signal, 310...Average value, 404...Secondary voltage history, 421...Discharge path length calculation unit, 422, 522, 623...Flow velocity calculation unit, 431...Flow velocity section determination unit, 432...Preliminary ignition signal generation unit, 504...Valve profile, 505...Crank angle, 506...Rotation speed, 507...Intake pressure, 508...Valve timing control unit, 509...Crank angle sensor, 521...Valve lift calculation unit, 604...Flow velocity map, 605...Operating conditions, 611...Map update unit, 612...Operating condition acquisition unit, 621...Map storage unit, 622...Map Selection Section

Claims (9)

An internal combustion engine control device that controls an internal combustion engine including a combustion chamber and an ignition device that generates a spark to ignite an air-fuel mixture in the combustion chamber,
a control unit that controls the ignition device during an intake stroke of a combustion cycle of the internal combustion engine to perform a preliminary ignition different from a main ignition for igniting the air-fuel mixture,
the control unit determines an ignition cycle and a frequency of a pre-ignition signal to be output to the ignition device in accordance with a flow state of the air-fuel mixture in the combustion chamber ,
The control unit divides the intake stroke into a high flow velocity section where the flow velocity of the air-fuel mixture is equal to or greater than a predetermined value and a low flow velocity section where the flow velocity of the air-fuel mixture is less than a predetermined value, and performs the pre-ignition preferentially in the high flow velocity section, and changes an ignition cycle and a frequency of the pre-ignition performed in the high flow velocity section.
Internal combustion engine control device. The internal combustion engine control device according to claim 1 , wherein the control unit increases the number of ignitions of the preliminary ignitions performed in the high flow velocity section to more than the number of ignitions of the preliminary ignitions performed in the low flow velocity section. 2. The internal combustion engine control device according to claim 1 , wherein the control unit makes a total amount of electrical energy used in the preliminary ignition performed in the high flow velocity section greater than a total amount of electrical energy used in the preliminary ignition performed in the low flow velocity section. the ignition device includes an ignition plug disposed in the combustion chamber and an ignition coil connected to the ignition plug,
The control unit, based on the value of the secondary voltage of the ignition coil when the ignition plug is energized,
The internal combustion engine control device according to claim 1 , wherein a flow state of the air-fuel mixture around the spark plug in the combustion chamber is estimated. the internal combustion engine has an intake port through which air passes to be drawn into the combustion chamber, and an intake valve provided in the intake port,
The internal combustion engine control device according to claim 1, wherein the control unit estimates a flow state of the mixture in the combustion chamber from a valve profile of the intake valve. 6. The internal combustion engine control device according to claim 5, wherein the control unit sets a period from the start of valve opening to the end of valve opening in a valve profile of the intake valve to a high flow velocity section in which a flow velocity of the air-fuel mixture is equal to or greater than a predetermined value, and performs the pre-ignition preferentially in the high flow velocity section. 2. The internal combustion engine control device according to claim 1, wherein the control unit estimates the flow state of the mixture in the combustion chamber corresponding to the current operating conditions using a map that associates operating conditions of the internal combustion engine with flow states of the mixture in the combustion chamber. A plurality of the internal combustion engines are provided,
The internal combustion engine control device according to claim 1, wherein the control unit determines an ignition period and a frequency of the pre-ignition signal to be output to each ignition device in accordance with a flow state of the air-fuel mixture in each combustion chamber. 1. A method for controlling an internal combustion engine including a combustion chamber and an ignition device that generates a spark to ignite an air-fuel mixture in the combustion chamber,
the control unit controls the ignition device during an intake stroke of a combustion cycle of the internal combustion engine to perform a preliminary ignition different from a main ignition for igniting the air-fuel mixture,
an internal combustion engine control method for performing the pre-ignition, estimating a flow state of the air-fuel mixture in the combustion chamber, dividing the intake stroke into a high flow velocity section where the flow velocity of the air-fuel mixture is equal to or greater than a predetermined value, and a low flow velocity section where the flow velocity of the air-fuel mixture is less than the predetermined value, performing the pre-ignition preferentially in the high flow velocity section, and determining an ignition period and a frequency of the pre-ignition signal to be output to the ignition device so that the ignition period and frequency of the pre-ignition performed in the high flow velocity section are changed .