Internal combustion engine control device and internal combustion engine control method

Abstract

To provide an internal combustion engine control device and an internal combustion engine control method that can reduce misfires in lean combustion, and can restrain deterioration of an ignition device.SOLUTION: An internal combustion engine control device comprises a control unit for controlling an ignition device in an intake stroke out of a combustion cycle of an internal combustion engine to cause it to perform preliminary ignition different from main ignition for igniting an air-fuel mixture. The control unit determines ignition periods and frequencies of preliminary ignition signals to be outputted to the ignition device in accordance with a flow mode of the air-fuel mixture in a combustion chamber.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an internal combustion engine control device and an internal combustion engine control method. [Background technology]

[0002] In recent years, there has been an increasing demand for improved fuel economy in gasoline engines for 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 that ensures the ignition of the mixture is required. In addition, 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 timing that does not ignite the fuel.

[0003] A technique for pre-ignition is described, for example, in Patent Document 1. Patent Document 1 discloses an ignition device for an internal combustion engine and a control device for a vehicle that performs pre-ignition by performing multiple discharges in an ignition plug from the exhaust stroke to the intake stroke as ignition control for lean burn. The ignition device for an internal combustion engine disclosed in Patent Document 1 ends pre-ignition before main ignition, which burns the air-fuel mixture, and before outputting a fuel injection signal. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2019 / 087748 Summary of the Invention [Problem to be solved by the invention]

[0005] 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 spark plug. Also, the increased energy input to the ignition coil causes the ignition coil to heat up, which may damage the ignition device or shorten its lifespan.

[0006] 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 performing pre-ignition and suppress deterioration of the ignition device. [Means for solving the problem]

[0007] 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 having a combustion chamber and an ignition device that generates a spark to ignite an 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 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 rate section where the flow rate of the mixture is equal to or greater than a predetermined value, and a low flow rate section where the flow rate of the mixture is less than the predetermined value, and performs the preliminary ignition preferentially in the high flow rate section, and changes the ignition period and frequency of the preliminary ignition performed in the high flow rate section. [Effects of the Invention]

[0008] According to the present invention, misfires during lean burn can be reduced and deterioration of the ignition device can be suppressed. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing an example of a basic configuration of an internal combustion engine according to a first embodiment. [Figure 2] 1 is a functional block diagram illustrating the functional configuration of an internal combustion engine control device according to a first embodiment. [Figure 3] 5 is a diagram showing the change over time in the flow velocity of the air-fuel mixture around the spark plug according to the first embodiment and the pre-ignition signal. FIG. [Figure 4] FIG. 6 is a functional block diagram illustrating the functional configuration of an internal combustion engine control device according to a second embodiment. [Figure 5] FIG. 10 is a functional block diagram illustrating the functional configuration of an internal combustion engine control device according to a third embodiment. [Figure 6]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. [Figure 7] FIG. 10 is a functional block diagram illustrating the functional configuration of an internal combustion engine control device according to a fourth embodiment. [Figure 8] FIG. 10 is a functional block diagram illustrating the functional configuration of an internal combustion engine control device according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] An internal combustion engine control device according to an embodiment will be described below. Note that common members in the various drawings are given the same reference numerals.

[0011] First Embodiment [Configuration of an 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.

[0012] The internal combustion engine 1 shown in FIG. 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.

[0013] 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, a crown surface 101P of the piston 101, and an inner wall 102a of the cylinder 102 form a combustion chamber 106.

[0014] An ignition device 110 is disposed 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 for igniting the air-fuel mixture M.

[0015] The combustion chamber 106 is in communication with 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.

[0016] 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. When a main ignition signal is sent to the ignition coil 112 at an appropriate timing, the electrode 113 of the spark plug 111 generates a spark.

[0017] When a spark is generated by the electrode 113, the air-fuel mixture M in the combustion chamber 106 is ignited, and the air-fuel mixture M in the combustion chamber 106 burns. This increases the pressure in the combustion chamber 106, pushing down the piston 101. As a result, the connecting rod 104 is displaced, and the crankshaft 105 rotates.

[0018] In recent years, in order to reduce carbon dioxide emissions generated when fuel is burned in an internal combustion engine, lean burn has been adopted, in which the fuel ratio in the air-fuel mixture M is reduced. 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 during combustion.

[0019] When a misfire occurs, the combustion speed decreases, generating hydrocarbons, which increases the amount of hydrocarbon emissions. Therefore, when lean burn is performed, measures to improve combustion are required when the internal combustion engine 1 is started 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 main ignition, thereby improving the combustibility of the air-fuel mixture M.

[0020] [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.

[0021] 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.

[0022] The flow velocity estimation unit 202 estimates the flow velocity of the air-fuel mixture M around the spark plug 111. Various information necessary for estimating 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 a sensor group 204. The various information includes the intake air amount, the crank angle, the secondary voltage of the ignition coil 112, the valve profile, the rotation speed of the internal combustion engine 1, the intake pressure, the coolant temperature, and the like.

[0023] The intake air amount is the amount of air that flows into the combustion chamber 106. The intake air amount is measured by an air flow sensor provided 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 provided radially outside a ring gear (not shown) attached to the crankshaft 105.

[0024] 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 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 of the internal combustion engine 1. The coolant temperature is measured by a water temperature sensor. The water temperature sensor is provided in a water jacket (not shown) of the cylinder head 103.

[0025] The information input to the flow velocity estimation unit 202 may be information about the combustion state in the previous combustion cycle and information about 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 a learning result or a map that associates operating conditions with estimated values ​​of the flow velocity of the mixture M from past operating data of the internal combustion engine 1.

[0026] The pre-ignition signal calculation unit 203 calculates the duration of pre-ignition, the start timing of pre-ignition, the period of pre-ignition (hereinafter referred to as the "ignition period"), the number of pre-ignitions (hereinafter referred to as the "number of ignitions"), the electrical energy used for pre-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 pre-ignition signal calculation unit 203 shortens the period of pre-ignition and reduces the electrical energy of pre-ignition.

[0027] The preliminary ignition signal calculation unit 203 generates a preliminary ignition signal (see FIG. 3) that repeats ON and OFF in accordance with the calculated preliminary ignition implementation period, start timing, ignition cycle, number of ignitions, electrical energy, etc. For example, to shorten the preliminary ignition cycle, the cycle of the preliminary ignition signal is shortened. Also, to reduce the electrical energy used for preliminary ignition, the number of times the preliminary ignition signal is ON (number of ignitions) is reduced or the frequency of the preliminary ignition signal is increased.

[0028] The preliminary ignition signal calculation unit 203 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 ignition plug 111, and multiple discharges (preliminary ignitions) are performed in accordance with the preliminary ignition signal.

[0029] 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. Incidentally, ozone contributes to the stability of combustion. Therefore, if the ozone generated by applying a high voltage to the electrode 113 is distributed approximately evenly within the combustion chamber 106, the stability of combustion in lean burn is improved. As a result, misfires that occur during combustion and the generation of hydrocarbons associated with misfires can be suppressed.

[0030] Chemical species such as ozone 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 makes it possible to reduce the number of pre-ignitions and the electrical energy required for pre-ignition.

[0031] [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.

[0032] 3, the flow of the air-fuel mixture M around the spark plug 111 is not constant but constantly fluctuates during the intake stroke 301. In particular, in an HEV (Hybrid Electric Vehicle) vehicle, the motoring speed at start-up is faster than in a vehicle equipped with only an internal combustion engine, so the fluctuation in flow velocity during the intake stroke becomes more pronounced.

[0033] The intake stroke 301 is made up of a high flow velocity section 302 and a low flow velocity section 303. The high flow velocity section 302 may be defined 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 an average value 310.

[0034] In the high flow velocity section 302, the flow velocity of the air-fuel 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.

[0035] On the other hand, in the low flow velocity section 303, the flow velocity of the air-fuel mixture M is relatively low. Therefore, in the low flow velocity 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 velocity section 303 does not improve the combustibility of the combustion chamber 106 as a whole, and the effect is limited.

[0036] 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 air-fuel mixture around the spark plug 111 may ignite, generating hydrocarbons. This may result in a deterioration of exhaust quality.

[0037] Furthermore, in the low flow velocity section 303, chemical species such as ozone generated by the discharge of the pre-ignition performed in the high flow velocity section 302 may be carried by the flow of the air-fuel mixture M and return to the vicinity of the ignition plug 111. If a discharge occurs there, the chemical species such as ozone may change into another chemical species, which may reduce the effectiveness of the pre-ignition.

[0038] Therefore, it is desirable to generate a preliminary ignition signal 304 that performs preliminary ignition preferentially 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 makes the number of ignitions and the total amount of electrical energy less than the number of ignitions and the total amount of electrical energy in the high flow velocity section 302.

[0039] In addition, 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.

[0040] Incidentally, pre-ignition is stabilized by changing the frequency (pulse width) and ignition period in accordance with the predicted flow velocity of the air-fuel mixture M. Therefore, a pre-ignition signal 307 may be generated whose frequency and ignition period are changed in accordance with the flow velocity of the air-fuel mixture M.

[0041] By preferentially performing pre-ignition in the high flow velocity section 302, the number of ignitions and the electrical energy used can be reduced compared to when pre-ignition is performed throughout the entire intake stroke 301. This reduces wear on the electrode 113 of the spark plug 111 and also prevents the ignition coil 112 from becoming too hot. As a result, deterioration of the ignition device 110 can be suppressed. Furthermore, since chemical species such as ozone are efficiently distributed throughout the combustion chamber 106, combustibility during main ignition can be improved.

[0042] 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.

[0043] 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.

[0044] The flow velocity estimation unit 402 has a discharge path length calculation unit 421 and a flow velocity calculation unit 422. The secondary voltage (secondary voltage history 404) of the ignition coil 112 in the preliminary ignition performed in the immediately previous combustion cycle is input to the discharge path length calculation unit 421. The control device 401 has a storage unit (not shown) that stores the secondary voltage history 404.

[0045] 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 value of the secondary voltage with the discharge path length. The discharge path length calculation unit 421 outputs the calculation result, that is, the discharge path length estimate value, to the flow velocity calculation unit 422.

[0046] 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 value. The flow velocity calculation unit 422 calculates the flow velocity of the mixture M using an equation that associates the length of the discharge path with 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.

[0047] 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.

[0048] The preliminary ignition signal generating 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 generating unit 432 may calculate the ignition period, number of ignitions, electrical energy, etc., taking into account the flow velocity of the air-fuel mixture M around the ignition plug 111.

[0049] The preliminary ignition signal generating unit 432 generates a preliminary ignition signal according to the duration of preliminary ignition, start timing, ignition cycle, number of ignitions, electrical energy, etc. Then, the preliminary ignition signal generating unit 432 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.

[0050] As described above, 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, and the flow velocity of the air-fuel mixture M around the spark plug 111 in the current combustion cycle is estimated. 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 FIG. 3).

[0051] 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, since chemical species such as ozone are efficiently distributed throughout the combustion chamber 106, combustibility during main ignition can be improved.

[0052] 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.

[0053] An 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 that 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.

[0054] A valve profile 504, a crank angle 505, a rotation speed 506, and an intake pressure 507 are input to the flow velocity estimation unit 502. The internal combustion engine system according to the third embodiment includes a rotation speed measurement unit (not shown) that measures the rotation speed 506 of the internal combustion engine 1, and a pressure sensor (not shown) that detects the intake pressure 507.

[0055] The internal combustion engine system according to the third embodiment also includes a valve timing control unit 508 that updates valve profile 504, and a crank angle sensor 509 that detects crank angle 505. Valve timing control unit 508, as represented by a VTC (variable timing camshaft) mechanism, changes the opening and closing timing of intake valve 123. Valve timing control unit 508 updates valve profile 504 when the opening and closing timing of intake valve 123 is changed.

[0056] 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 with respect 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.

[0057] 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, the rotation speed 506, and the 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 the preliminary ignition signal generation unit 432 of the preliminary ignition signal calculation unit 403 is the same as in the second embodiment, and therefore description thereof will be omitted.

[0058] In the third 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 reduces wear on the electrode 113 of the spark plug 111 and also 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.

[0059] 6, at the time when intake valve 123 starts to open, the difference between intake pressure 507 and the pressure inside combustion chamber 106 is large, so a large amount of mixture M flows into combustion chamber 106, or mixture M flows back toward cylinder head 103. At this time, the flow of mixture M inside combustion chamber 106, including the area around spark plug 111, becomes strong. Therefore, the flow speed of mixture M around spark plug 111 increases.

[0060] On the other hand, at the time when the intake valve 123 finishes opening, the pressure in the combustion chamber 106 and the intake pressure become close to each other, so the flow of gas into the combustion chamber 106 becomes gentle. This weakens the flow of the mixture M in the combustion chamber 106, including the area around the spark plug 111. Therefore, the flow speed of the mixture M around the spark plug 111 becomes slower.

[0061] 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.

[0062] <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.

[0063] An 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.

[0064] A flow velocity map 604 and operating conditions 605 of the internal combustion engine 1 are input to the flow velocity estimation unit 602. The operating conditions 605 include, for example, the rotation speed of the internal combustion engine 1, intake pressure, throttle opening, coolant temperature, intake air amount, fuel injection amount, crank angle, etc.

[0065] 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 operating conditions 605. The operating condition acquisition unit 612 may include, for example, a throttle opening sensor that detects the opening of the throttle, a fuel flow meter that measures the amount of fuel injection, or the like.

[0066] 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 by, for example, using a three-dimensional fluid simulation to obtain a change over time in the flow velocity of the air-fuel mixture M around the spark plug 111 for the operating conditions 605. Alternatively, the flow velocity map 604 may define a high flow velocity section 302 for the operating conditions 605.

[0067] 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) a plurality of supplied flow velocity maps 604. The map selection unit 622 selects a flow velocity map 604 that corresponds to the operating conditions 605 at that time from the plurality of flow velocity maps 604 stored in the map storage unit 621.

[0068] 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 section determination unit 431 and the preliminary ignition signal generation unit 432 of the preliminary ignition signal calculation unit 403 is the same as in the second embodiment, and therefore description thereof will be omitted.

[0069] In the fourth embodiment, pre-ignition is also performed preferentially in the high flow velocity 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 reduces wear on the electrode 113 of the spark plug 111 and also 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 the combustibility of the air-fuel mixture M during main ignition.

[0070] 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.

[0071] 8, the internal combustion engine system according to the fifth embodiment includes a plurality of internal combustion engines 1A, 1B, ..., 1X. The plurality of internal combustion engines 1A, 1B, ..., 1X each have an ignition plug 111A, 111B, ..., 111X and an ignition coil 112A, 112B, ..., 112X.

[0072] An 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.

[0073] The flow velocity estimation unit 702 estimates the flow velocity of the air-fuel mixture M around each of the spark plugs 111A, 111B, ..., 111X. Various information necessary for estimating the flow velocity of the air-fuel mixture M around each of the spark plugs 111A, 111B, ..., 111X is input to the flow velocity estimation unit 702. The various information is detected or measured by a sensor group 704. The various information includes the intake air amount, crank angle, secondary voltage of the ignition coils 112A, 112B, ..., 112X, valve profile, rotation speed of the internal combustion engine 1, intake pressure, coolant temperature, etc., related to each of the internal combustion engines 1A, 1B, ..., 1X.

[0074] The preliminary ignition signal calculation unit 703 calculates the duration, start timing, ignition cycle, number of ignitions, electrical energy, etc. of preliminary ignition for each ignition device based on the flow speed of the air-fuel mixture M around each of the spark plugs 111A, 111B, ... 111X. Then, the preliminary ignition signal calculation unit 703 generates a preliminary ignition signal for each ignition device according to the calculated duration, start timing, ignition cycle, number of ignitions, electrical energy, etc. of preliminary ignition.

[0075] The preliminary ignition signal calculation unit 703 outputs the generated preliminary ignition signal to the ignition coils 112A, 112B, ..., 112X. As a result, a high voltage is applied to each electrode of the ignition plugs 111A, 111B, ..., 111X, and a plurality of discharges (preliminary ignitions) are performed in accordance with the preliminary ignition signal.

[0076] The flow state of the mixer M in the combustion chamber of each of the internal combustion engines 1A, 1B, ..., 1X is affected by the valve timing, the fluctuation of the intake pressure, the orientation of the spark plugs 111A, 111B, ..., 111X, etc. As a result, the flow state of the mixer M in the combustion chamber of each of the internal combustion engines 1A, 1B, ..., 1X differs from one another.

[0077] Therefore, the pre-ignition signal calculation unit 703 determines the optimal pre-ignition implementation period, 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 of the internal combustion engines 1A, 1B...1X. Then, the pre-ignition signal calculation unit 703 generates a pre-ignition signal for each of the internal combustion engines 1A, 1B...1X. This makes it possible to reduce the number of misfires and the generation of hydrocarbons for each of the internal combustion engines 1A, 1B...1X.

[0078] Furthermore, the number of pre-ignition ignitions and the electrical energy used can be reduced for each of the internal combustion engines 1A, 1B, ..., 1X. This can reduce electrode wear of each of the spark plugs 111A, 111B, ..., 111X, and prevent the ignition coils 112A, 112B, ..., 112X from becoming too hot. As a result, deterioration of the ignition devices of each of the internal combustion engines 1A, 1B, ..., 1X can be suppressed. Furthermore, because chemical species such as ozone are efficiently distributed within the combustion chambers of each of the internal combustion engines 1A, 1B, ..., 1X, the combustibility of the air-fuel mixture M during main ignition in each of the internal combustion engines 1A, 1B, ..., 1X can be improved.

[0079] <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 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 according to 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 also 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.

[0080] 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 preferentially performs pre-ignition 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.

[0081] The preliminary ignition signal calculation unit 403 (control unit) according to the second embodiment described above increases the number of preliminary ignitions performed in the high flow velocity section 302 compared to 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.

[0082] 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.

[0083] The flow velocity estimation unit 402 (control unit) according to the second embodiment described above estimates the flow state of the air-fuel 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 the spark plug 111 is energized. This eliminates the need to provide a detection unit for detecting the flow state of the air-fuel mixture M in 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 in the combustion chamber 106 without changing the configuration of the internal combustion engine 1.

[0084] The flow velocity estimation unit 502 (control unit) according to the third embodiment described above estimates the flow state of the 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 in 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 in the combustion chamber 106 without changing the configuration of the internal combustion engine 1.

[0085] 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 to 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.

[0086] 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 in 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 in the combustion chamber 106 without changing the configuration of the internal combustion engine 1.

[0087] A plurality of internal combustion engines according to the fifth embodiment are provided. 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 according to 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 mixture M at the time of main ignition in each of the internal combustion engines 1A, 1B, ..., 1X.

[0088] In the internal combustion engine control method according to this embodiment, a flow velocity estimation unit 202 and a preliminary 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 preliminary ignition that is different from main ignition for igniting the air-fuel mixture M. When performing preliminary ignition, the flow velocity estimation unit 202 estimates the flow state of the air-fuel mixture M in the combustion chamber 106. Then, the preliminary ignition signal calculation unit 203 determines the ignition period and frequency of the preliminary ignition signal to be output to the ignition device 110 according to 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 also 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.

[0089] The present invention is not limited to the embodiments described above and shown in the drawings, and various modifications can be made without departing from the spirit of the invention as defined in the claims.

[0090] Furthermore, 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. Furthermore, it is 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. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with another configuration. [Explanation of symbols]

[0091] 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...pre-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...pre-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

1. 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.

2. The control unit increases the number of times of ignition of the preliminary ignition performed in the high flow velocity section to be greater than the number of times of ignition of the preliminary ignition performed in the low flow velocity section. The internal combustion engine control device according to claim 1.

3. The control unit sets a total amount of electric energy used in the preliminary ignition performed in the high flow velocity section to be greater than a total amount of electric energy used in the preliminary ignition performed in the low flow velocity section. The internal combustion engine control device according to claim 1.

4. 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, A flow state of the air-fuel mixture around the spark plug in the combustion chamber is estimated. The internal combustion engine control device according to claim 1.

5. 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 control unit estimates a flow state of the mixture in the combustion chamber from a valve profile of the intake valve. The internal combustion engine control device according to claim 1.

6. 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 as 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. The internal combustion engine control device according to claim 5.

7. 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. The internal combustion engine control device according to claim 1.

8. A plurality of the internal combustion engines are provided, The control unit determines the ignition period and frequency of the preliminary ignition signal to be output to each ignition device according to the flow state of the air-fuel mixture in each combustion chamber. The internal combustion engine control device according to claim 1.

9. 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, When the preliminary ignition is performed, the flow state of the air-fuel mixture in the combustion chamber is estimated, the intake stroke is divided 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, the preliminary ignition is performed preferentially in the high flow velocity section, and an ignition period and a frequency of the preliminary ignition signal to be output to the ignition device are determined so that the ignition period and frequency of the preliminary ignition performed in the high flow velocity section are changed. Internal combustion engine control method.

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