Internal combustion engine control device

Abstract

The present invention provides an internal combustion engine control device, which includes an ignition timing estimation unit, a crank angle information acquisition unit, a rotation change acquisition unit and a jet flame intensity estimation unit. The ignition timing estimation unit estimates the ignition timing based on a knock sensor signal detected by a knock sensor. The rotation change acquisition unit calculates the speed change amount generated after the ignition timing based on the crank angle information. The jet flame intensity estimation unit calculates the speed change rate that occurs after the ignition timing and estimates the jet flame intensity based on the speed change amount calculated by the rotation change acquisition unit and the ignition timing estimated by the ignition timing estimation unit.

Description

Technical Field

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

[0002] Conventionally, gasoline engines are known that form a fuel-air mixed gas in a combustion chamber and burn it by ignition or self-ignition. As a technology for improving the thermal efficiency of such an engine, there is a sub-chamber type jet flame ignition (hereinafter referred to as sub-chamber combustion) system that ignites the mixed gas in a sub-chamber that is a tiny space of several cc and sprays the jet flame into the main combustion chamber.

[0003] In a general gasoline engine, a spark plug is fixed to the upper part of the main combustion chamber in a manner that its front end is exposed in the combustion chamber. Then, when combustion starts, a spark caused by discharge generated by the spark plug directly ignites the mixed gas in the main combustion chamber.

[0004] On the other hand, in the sub-chamber combustion, a sub-chamber is provided at the upper part of the combustion chamber, and the spark plug is fixed in a manner exposed in the sub-chamber. In the sub-chamber, a sub-chamber injection hole connected to the main combustion chamber is provided. When the combustion starts, the mixed gas is first ignited inside the sub-chamber. Then, after the combustion in the sub-chamber occurs, a jet flame containing a high-temperature and unburned mixed gas is ejected from the sub-chamber injection hole to the main combustion chamber side, and the mixed gas on the main combustion chamber side is ignited by the jet flame. Ignition occurs simultaneously at multiple points in the main combustion chamber, and the combustion progresses rapidly compared to the case where the sub-chamber is not used, so the stability of the combustion is improved.

[0005] Through the sub-chamber combustion, it is possible to implement lean combustion in a more dilute state, which makes the fuel mixture more lean than the theoretical air-fuel ratio. The increase in the adiabatic index of the mixed gas leads to an increase in the theoretical thermal efficiency and a reduction in pumping losses, which improves the thermal efficiency. In addition, it is possible to make the combustion gas reach the abnormal combustion occurrence area before abnormal combustion such as knock occurs, and as a result, the knock suppression effect can also be obtained. As a result, the optimal ignition timing can be achieved even in the high load range, and the exhaust loss is reduced compared to the case where the sub-chamber is not used, and the thermal efficiency is further improved.

[0006] In addition, as a technology for controlling an internal combustion engine having an auxiliary combustion chamber, there is a technology described in, for example, Patent Document 1. Patent Document 1 describes a technology having a pressure sensor for detecting the pressure of the auxiliary combustion chamber and an ignition control unit for controlling the ignition of a spark plug according to the operating state of the internal combustion engine and the detected pressure in the auxiliary combustion chamber.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2018-178966 Summary of the invention

[0010] Problems to be solved by the invention

[0011] However, the technique described in Patent Document 1 requires a pressure sensor for detecting the pressure of the sub chamber, which causes a problem of increased system cost.

[0012] In addition, the higher the intensity of the jet flame ejected from the secondary chamber, the more stable the ignition of the mixed gas can be. However, when the jet flame intensity is too high, the heat loss of the secondary chamber wall surface and the main combustion chamber wall surface increases, resulting in an increase in fuel consumption and a decrease in the fuel consumption reduction effect achieved by the secondary chamber combustion. Furthermore, when the jet flame intensity is further increased, there is also a risk that the pressure fluctuation of the main combustion chamber caused by the jet flame ejection will cause knocking. Therefore, in order to adjust the jet flame intensity to an appropriate range while maintaining a balance between combustion stability and heat loss, it is required to accurately estimate the jet flame intensity.

[0013] An object of the present invention is to provide an internal combustion engine control device capable of estimating the jet flame intensity without using a pressure sensor for detecting the pressure of a sub chamber in consideration of the above-mentioned problem.

[0014] Technical solutions to solve problems

[0015] In order to solve the above problems and achieve the purpose, the internal combustion engine control device controls the internal combustion engine including the main combustion chamber facing the piston, the auxiliary combustion chamber, the spark plug, the crankshaft, the crank angle sensor, the cylinder and the knock sensor. In addition, the auxiliary combustion chamber is connected to the main combustion chamber. The spark plug is installed inside the auxiliary combustion chamber. The crankshaft is connected to the piston. The crank angle sensor detects the rotation angle of the crankshaft. The cylinder forms the main combustion chamber. The knock sensor detects the vibration of the cylinder.

[0016] The internal combustion engine control device includes an ignition timing estimation unit, a crank angle information acquisition unit, a rotation variation acquisition unit, and a jet flame intensity estimation unit.

[0017] The ignition timing estimation unit estimates the ignition timing of the mixture gas of the main combustion chamber from the jet flame injected from the auxiliary combustion chamber based on the knock sensor signal detected by the knock sensor. The crank angle information acquisition unit acquires the crank angle information detected by the crank angle sensor. The rotation change acquisition unit calculates the speed change amount occurring after the ignition timing based on the crank angle information. The jet flame intensity estimation unit calculates the speed change rate occurring after the ignition timing and estimates the jet flame intensity based on the speed change amount calculated by the rotation change acquisition unit and the ignition timing estimated by the ignition timing estimation unit.

[0018] Effects of the Invention

[0019] According to the internal combustion engine control device having the above configuration, the jet flame intensity can be accurately estimated without using a pressure sensor for detecting the pressure of the sub chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic configuration diagram showing a system configuration of an internal combustion engine equipped with an internal combustion engine control device according to a first embodiment.

[0021] Figure 2 It is a schematic configuration diagram showing the configuration of the cylinder periphery of an internal combustion engine equipped with an internal combustion engine control device according to the first embodiment.

[0022] Figure 3 It is a block diagram showing the configuration of the internal combustion engine control device according to the first embodiment.

[0023] Figure 4 This is a block diagram showing a configuration of a jet flame intensity estimation process in the internal combustion engine control device according to the first embodiment.

[0024] FIG. 5A to FIG. 5C is a diagram illustrating the combustion consumption and heat loss determined by the difference in jet flame intensity, where Figure 5A This is a diagram showing the difference between the pressure of the sub chamber and the pressure of the main combustion chamber due to the difference in the jet flame intensity. Figure 5B This is a graph showing the relationship between the difference in jet flame intensity and the combustion consumption rate. Figure 5C This is a graph showing the relationship between the difference in jet flame intensity and the amount of heat loss.

[0025] Figure 6 Indicates changes in pressure, differential pressure, rotation speed, and vibration (acceleration) in the sub chamber and main combustion chamber during one combustion cycle. Figure 6 (a) represents the pressure of the secondary chamber, Figure 6 (b) represents the pressure in the main combustion chamber, Figure 6 (c) represents the pressure difference, Figure 6 (d) represents the rotation speed, Figure 6 (e) represents vibration (acceleration).

[0026] Figure 7 It is a schematic diagram showing a conventional method for estimating the rotation speed change rate and a method for estimating the rotation speed change rate in the internal combustion engine control device according to the first embodiment.

[0027] Figure 8 FIG. 2 shows signal processing of a knock sensor signal in the internal combustion engine control device according to the first embodiment. Figure 8 (a) is a waveform showing the output value of the knock sensor, Figure 8 (b) is a waveform showing a filter output value obtained by filtering the knock sensor signal. Figure 8 (c) is a graph showing the absolute value of the filter output value.

[0028] Fig. 9It is a diagram showing the accuracy of the conventional estimation result of the jet flame intensity and the estimation result of the jet flame intensity estimated by the internal combustion engine control device according to the first embodiment.

[0029] Fig.10 This is a flowchart showing the correction control operation of the jet flame intensity in the internal combustion engine control device according to the first embodiment.

[0030] Fig.11A and Fig. 11B FIG. 1 shows the increase / decrease process of the jet flame intensity in the internal combustion engine control device according to the first embodiment, wherein: Fig.11A is a diagram showing an example of increase and decrease processing, Fig. 11B It is a diagram showing another example of increase and decrease processing.

[0031] Fig. 12A and Fig. 12B FIG. 1 shows the increase / decrease process of the jet flame intensity in the internal combustion engine control device according to the first embodiment, wherein: Fig. 12A is a diagram showing an example of increase and decrease processing, Fig. 12B It is a diagram showing another example of increase and decrease processing.

[0032] Fig.13 This is a block diagram showing a configuration of a jet flame intensity estimation process in an internal combustion engine control device according to a second embodiment.

[0033] Fig.14 This is a map showing the knock sensor amplitude confidence ratio when estimating the jet intensity under each engine operating condition in the internal combustion engine control device according to the second embodiment.

[0034] Fig.15 It is a diagram showing a method of estimating the jet intensity by the second jet intensity estimating unit of the internal combustion engine control device according to the second embodiment.

[0035] Fig.16 This is a graph showing the correlation between the jet flame intensity and the initial combustion period.

[0036] Fig.17 This is a diagram showing changes in the in-cylinder pressure and torque of the main combustion chamber during one combustion cycle.

[0037] Fig.18 It is a diagram showing an example of the changing state of the jet flame and the pressure difference ΔP.

[0038] Fig.19 This is a control timing chart for explaining the detection of combustion timing in the internal combustion engine control device according to the fifth embodiment.

[0039] Fig. 20 It is a schematic structural diagram showing an enlarged structure of the periphery of a sub chamber of an internal combustion engine according to a modified example. DETAILED DESCRIPTION

[0040] Hereinafter, the internal combustion engine control device of the embodiment example will be referred to as follows. Figures 1 to 20 In addition, the same reference numerals are attached to common components in each figure.

[0041] 1. First embodiment example

[0042] First, a configuration example of an internal combustion engine control device according to a first embodiment (hereinafter referred to as “this example”) will be described.

[0043] 1-1. Example of the structure of an internal combustion engine

[0044] First, refer to Figure 1 and Figure 2 A structural example of an internal combustion engine will be described.

[0045] Figure 1 It is a schematic structural diagram showing the system structure of the internal combustion engine of this example. Figure 2 This is a schematic structural diagram showing the structure around a cylinder of an internal combustion engine.

[0046] Figure 1 The internal combustion engine 100 shown is an in-cylinder injection type internal combustion engine (direct injection engine) that directly injects fuel composed of gasoline into the cylinder. The internal combustion engine 100 is a four-stroke engine that repeats four strokes, namely, an intake stroke, a compression stroke, a combustion (expansion) stroke, and an exhaust stroke. Furthermore, the internal combustion engine 100 is, for example, a multi-cylinder engine having four cylinders. In addition, the number of cylinders of the internal combustion engine 100 is not limited to four, and it may also have six or eight or more cylinders.

[0047] like Figure 1 As shown, the internal combustion engine 100 includes an air flow sensor 1, an electronically controlled throttle valve 2, an intake pressure sensor 3, a supercharger 4, an intercooler 7, and a cylinder 14. The air flow sensor 1, the electronically controlled throttle valve 2, the intake pressure sensor 3, the compressor 4a of the supercharger 4, and the intercooler 7 are arranged at a position in the intake pipe 6 that reaches the cylinder 14.

[0048] The air flow sensor 1 measures the intake air amount and the intake air temperature. The electronically controlled throttle valve 2 is driven to open and close by a drive motor (not shown). Then, based on the driver's acceleration operation, the opening of the electronically controlled throttle valve 2 is adjusted. Thus, the amount of air sucked into the intercooler 7 and the cylinder 14 is adjusted.

[0049] The compressor 4a is a supercharger for supercharging the intake air. The compressor 4a transmits the rotational force through the turbine 4b described later. The intercooler 7 is arranged on the upstream side of the cylinder 14 and on the downstream side of the electronically controlled throttle valve 2 and the air flow sensor 1. In addition, the intercooler 7 cools the intake air.

[0050] In addition, the internal combustion engine 100 Figure 1 and Figure 2 As shown, an injector 13 for injecting fuel into the cylinder 14, an ignition device composed of an ignition coil 16 and a spark plug 17 for supplying ignition energy, a sub chamber 8, and a knock sensor 47 are provided for each cylinder 14. The ignition coil 16 generates a high voltage under the control of the internal combustion engine control device 20 and applies it to the spark plug 17. As a result, a spark is generated in the spark plug 17.

[0051] In addition, if Figure 2 As shown, the spark plug 17 is arranged in the sub-chamber 8 provided in the cylinder 14. The hollow sub-chamber 8 is inserted into the cylinder of the cylinder 14. Therefore, the internal combustion engine 100 of this example is divided into a main combustion chamber 14a formed in the cylinder of the cylinder 14 and a sub-combustion chamber formed by the sub-chamber 8. The sub-chamber 8 is fixed to the cylinder head in a state where its front end portion is exposed in the main combustion chamber 14a. A sub-chamber injection hole 8a communicating with the main combustion chamber 14a is formed at the front end portion of the sub-chamber 8. The sub-chamber formed by the sub-chamber 8 is connected to the main combustion chamber 14a through the sub-chamber injection hole 8a. Then, the mixed gas is introduced into the sub-chamber 8 from the main combustion chamber 14a through the sub-chamber injection hole 8a.

[0052] In addition, the mixed gas in the auxiliary combustion chamber burns due to the spark generated by the spark plug 17. Then, the flame generated in the auxiliary chamber 8 is ejected into the main combustion chamber 14a as a plurality of jet flames through the auxiliary chamber injection hole 8a, ignites the mixed gas in the main combustion chamber 14a, and performs main combustion. Hereinafter, the jet flame ejected from the auxiliary chamber injection hole 8a is simply referred to as the jet flame. As a result, ignition occurs at multiple points in the main combustion chamber 14a at the same time, and the combustion progresses rapidly compared to the case where the auxiliary chamber 8 is not used, and the stability of the combustion is improved. Hereinafter, the jet flame ejected from the auxiliary chamber injection hole 8a is simply referred to as the jet flame.

[0053] In addition, a voltage sensor (not shown) is attached to the ignition coil 16. The voltage sensor measures the primary side voltage or the secondary side voltage of the ignition coil 16. Then, the voltage information measured by the voltage sensor is sent to the ECU (Engine Control Unit), that is, the internal combustion engine control device 20.

[0054] In addition, a variable valve 5 is provided on the cylinder head of the cylinder 14. Figure 2As shown, there are an intake side timing mechanism 5a, an exhaust side timing mechanism 5b, an intake valve 31 and an exhaust valve 32. The intake valve 31 is arranged at the intake port connected to the intake pipe 6 in the cylinder 14, and the exhaust valve 32 is arranged at the exhaust port connected to the exhaust pipe 15 described later in the cylinder 14.

[0055] The variable valve 5 adjusts the opening and closing timing of the intake valve 31 and the exhaust valve 32 by using the intake side timing mechanism 5a and the exhaust side timing mechanism 5b. This adjusts the mixed gas flowing into the cylinder 14 or the exhaust gas discharged from the cylinder. By adjusting the variable valve 5, the intake amount and the internal EGR amount of all cylinders 14 are adjusted.

[0056] Furthermore, a piston 18 is slidably disposed in the cylinder 14. The piston 18 compresses the mixed gas of fuel and gas flowing into the cylinder 14. Then, the piston 18 reciprocates in the cylinder 14 due to the combustion pressure generated in the cylinder. The piston 18 is connected to the crankshaft 48 via a connecting rod.

[0057] In addition, a crank angle sensor 49 is provided for detecting the angle of the crankshaft 48. The crank angle sensor 49 detects teeth provided at predetermined angle intervals (for example, 6 degrees) in the circumferential direction of the crankshaft 48.

[0058] In addition, the knock sensor 47 is mounted on the side portion of the cylinder 14 or on the cylinder head. The knock sensor 47 is an acceleration sensor that detects the vibration of the cylinder 14. The position where the knock sensor 47 is set is not limited to the side portion of the cylinder 14, for example, any position that can detect the vibration of the cylinder 14, such as the upper portion of the cylinder head, will suffice. The vibration signal (acceleration information) of the cylinder 14 detected by the knock sensor 47 is output to the internal combustion engine control unit (ECU) 20 described later. Then, when it is determined that the vibration signal from the knock sensor 47 exceeds a preset knock threshold, the ECU 20 detects the occurrence of knock.

[0059] The injector 13 is controlled by an internal combustion engine control unit (ECU) 20 described later, and injects fuel into the cylinder 14. As a result, a mixed gas of air and fuel is generated in a main combustion chamber 14a in the cylinder 14. In addition, a high-pressure fuel pump (not shown) is connected to the injector 13. The high-pressure fuel pump supplies the fuel with increased pressure to the injector 13. Furthermore, a fuel pressure sensor for measuring the fuel injection pressure is provided in the fuel pipe connecting the injector 13 and the high-pressure fuel pump.

[0060] In addition, in this example, the injector 13 is provided in the cylinder 14, but the present invention is not limited to this. For example, the port injection injector 13B may be installed in the intake pipe 6, and the fuel may be injected into the intake port from the port injection injector 13B.

[0061] like Figure 1 As shown, a turbine 4b, an electronically controlled wastegate valve 11, a three-way catalyst 10, and an air-fuel ratio sensor 9 are provided in an exhaust pipe 15. The turbine 4b is rotated by the exhaust gas passing through the exhaust pipe 15, and transmits a rotational force to the compressor 4a. The electronically controlled wastegate valve 11 regulates the exhaust gas flow path to the turbine 4b.

[0062] The three-way catalyst 10 purifies harmful substances contained in the exhaust gas by oxidation-reduction reaction. In addition, the air-fuel ratio sensor 9 is arranged on the upstream side of the three-way catalyst 10. The air-fuel ratio sensor 9 detects the air-fuel ratio of the exhaust gas passing through the exhaust pipe 15.

[0063] The internal combustion engine 100 has an EGR flow pipe 40 for recirculating the exhaust gas (EGR gas) from the downstream of the three-way catalyst 10 to the upstream of the compressor 4a and the downstream of the air flow sensor 1. The EGR flow pipe 40 is provided with an EGR cooler 42, an EGR valve 41 and a differential pressure sensor 43.

[0064] The EGR cooler 42 cools the EGR gas. The EGR valve 41 controls the EGR flow rate that regulates the flow rate of the EGR gas passing through the EGR flow pipe 40. A differential pressure sensor 43 that detects the pressure difference before and after the EGR valve 41 is installed near the EGR valve 41. Here, the differential pressure before and after the EGR valve 41 refers to the difference between the pressure on the upstream side and the pressure on the downstream side of the EGR valve 41 in the EGR flow pipe 40. The EGR temperature sensor 44 is arranged downstream of the EGR valve 41. The EGR temperature sensor 44 detects the temperature of the EGR gas flowing in the EGR flow pipe 40.

[0065] A portion of the exhaust gas purified by the three-way catalyst 10 is not discharged to the outside, but flows into the EGR flow pipe 40 and is used as EGR gas. The EGR gas passes through the EGR cooler 42 and the EGR valve 41, and then merges with the fresh air sucked in upstream of the compressor 4a. After that, the mixed gas of the EGR gas and the fresh air passes through the intercooler 7 and the electronically controlled throttle valve 2, and then flows into the cylinder 14.

[0066] In addition, the signals detected by the air flow sensor 1, the intake pressure sensor 3, the knock sensor 47 and other sensors are sent to the ECU (Engine Control Unit), that is, the internal combustion engine control device 20. In addition, the signal detected by the accelerator pedal opening sensor 12 that detects the amount of accelerator pedal depression, that is, the accelerator pedal opening, is also sent to the internal combustion engine control device 20.

[0067] The internal combustion engine control device 20 calculates the required torque based on the output signal of the accelerator pedal opening sensor 12. That is, the accelerator pedal opening sensor 12 is used as a required torque detection sensor for detecting the required torque of the internal combustion engine 100. In addition, the internal combustion engine control device 20 calculates the rotation speed of the internal combustion engine 100 based on the output signal of the crank angle sensor (not shown). Moreover, the internal combustion engine control device 20 optimally calculates the main operation quantities of the internal combustion engine 100, such as the air flow rate, the fuel injection amount, the ignition timing, and the fuel pressure, based on the operating state of the internal combustion engine 100 obtained from the outputs of various sensors.

[0068] The fuel injection amount calculated by the internal combustion engine control device 20 is converted into a valve opening pulse signal and output to the injector 13. In addition, the ignition timing (Japanese: period) calculated by the internal combustion engine control device 20 is output as an ignition signal to the spark plug 17. Furthermore, the throttle valve opening calculated by the internal combustion engine control device 20 is output as a throttle valve drive signal to the electronically controlled throttle valve 2. In addition, the EGR valve opening calculated by the internal combustion engine control device 20 is output as an EGR valve opening drive signal to the EGR valve 41.

[0069] 1-2. Configuration Example of Internal Combustion Engine Control Device 20

[0070] Next, refer to Figure 3 A configuration example of the internal combustion engine control device 20 will be described.

[0071] Figure 3 It is a block diagram showing the structure of the internal combustion engine control device 20.

[0072] like Figure 3 As shown, the ECU (Engine Control Unit), i.e., the internal combustion engine control device 20, includes an input circuit 21, an input / output port 22, a RAM (Random Access Memory) 23c, a ROM (Read Only Memory) 23b, and a CPU (Central Processing Unit) 23a. In addition, the internal combustion engine control device 20 includes an ignition control unit 24.

[0073] The input circuit 21 receives the intake flow rate from the air flow sensor 1, the intake pressure from the intake pressure sensor 3, and the primary voltage or secondary voltage of the coil from the voltage sensor. In addition, the input circuit 21 receives information measured by various sensors, such as the accelerator pedal opening, the rotation speed, the humidity, the air volume, the crank angle, the ignition device information, and the knock sensor information.

[0074] The input circuit 21 performs signal processing such as noise removal on the input signal, and sends the signal to the input / output port 22. The value input to the input port of the input / output port 22 is stored in the RAM 23c.

[0075] The ROM 23b stores a control program describing the contents of various calculation processes to be executed by the CPU 23a, and a MAP and a data table used in each process. The RAM 23c stores a storage area for storing values ​​input to the input port of the input / output port 22 and values ​​representing the operation amount of each actuator calculated according to the control program. In addition, the values ​​representing the operation amount of each actuator stored in the RAM 23c are sent to the output port of the input / output port 22.

[0076] The ignition signal set to the output port of the input / output port 22 is sent to the ignition coil 16 via the ignition control unit 24. The ignition control unit 24 controls the energization timing and energization time of the ignition coil 16. Furthermore, the ignition control unit 24 controls the discharge energy in the spark plug 17.

[0077] In this example, the ignition control unit 24 is provided in the internal combustion engine control device 20, but the present invention is not limited thereto. For example, part of the ignition control unit 24 or the entire ignition control unit 24 may be installed in a control device different from the internal combustion engine control device 20.

[0078] Furthermore, the internal combustion engine control device 20 estimates the intensity of the jet flame injected from the sub chamber injection hole 8 a of the sub chamber 8 based on output signals from various sensors, and controls the ignition timing in the spark plug 17 .

[0079] 1-3. Configuration Example of Estimation Processing of Jet Flame Intensity in the Internal Combustion Engine Control Device 20

[0080] Next, refer to Figure 4 A configuration example of the estimation process of the jet flame intensity in the internal combustion engine control device 20 will be described.

[0081] Figure 4 1 is a block diagram showing a configuration of a jet flame intensity estimation process in the internal combustion engine control device 20 .

[0082] like Figure 4 As shown, the internal combustion engine control device 20 includes a knock sensor signal acquisition unit 101, a bandwidth / threshold value acquisition unit 102, a crank angle information acquisition unit 103, a rotation variation acquisition unit 104, an ignition timing estimation unit 105, and a crankshaft acceleration start timing estimation unit 106. Furthermore, the internal combustion engine control device 20 includes a jet flame intensity estimation unit 107, a jet flame intensity comparison unit 108, an ignition timing output unit 109, and a jet flame intensity upper limit value / lower limit value calculation unit 110.

[0083] Knock sensor signal acquisition unit 101 is connected to knock sensor 47 and acquires a knock sensor signal from knock sensor 47 and vibration information, that is, acceleration information, of cylinder 14. Knock sensor signal acquisition unit 101 is connected to ignition timing estimation unit 105 and outputs the acquired knock sensor signal to ignition timing estimation unit 105.

[0084] The bandwidth / threshold value acquisition unit 102 receives inputs such as engine speed information and engine shape information. The engine shape information is the number of cylinders 14 mounted in the engine, that is, the number of cylinders. The bandwidth / threshold value acquisition unit 102 acquires the set value of the bandwidth when the knock sensor signal is filtered in the ignition timing estimation unit 105, and the threshold value used in the ignition timing estimation process, based on the engine speed information and the engine shape information. The bandwidth / threshold value acquisition unit 102 outputs the acquired bandwidth and threshold value to the ignition timing estimation unit 105.

[0085] The bandwidth / threshold value acquisition unit 102 sets the low-frequency side of the bandwidth in a manner that does not include the natural vibration frequency of the engine and the mechanical vibration caused by the rotation. That is, the higher the engine speed, the higher the natural vibration frequency, so the lower limit value of the bandwidth is set to be larger. In addition, the natural vibration frequency varies depending on the number of cylinders of the engine, that is, whether it is a four-cylinder engine or a three-cylinder engine. Therefore, the bandwidth / threshold value acquisition unit 102 changes the lower limit value of the bandwidth based on the number of cylinders of the engine as the control object so that the natural vibration frequency is not included in the set value of the bandwidth.

[0086] In addition, the amplitude of the mechanical vibration decreases as the engine speed decreases or the engine load decreases. Therefore, the bandwidth / threshold value acquisition unit 102 sets the threshold value to be smaller as the engine speed and the engine load decrease.

[0087] The ignition timing estimation unit 105 performs filtering processing on the knock sensor signal output from the knock sensor signal acquisition unit 101 based on the bandwidth output from the bandwidth / threshold value acquisition unit 102, and extracts the combustion component. Furthermore, the ignition timing estimation unit 105 estimates the ignition timing of the jet (jet flame start timing t jet Then, the ignition timing estimation unit 105 outputs the estimated ignition timing to the crank acceleration start timing estimation unit 106.

[0088] The crankshaft acceleration start timing estimation unit 106, which represents the ignition timing correction unit, estimates the time when the crankshaft 48 starts to accelerate, that is, the crankshaft acceleration start timing t , based on the ignition timing output from the ignition timing estimation unit 105 and the pre-stored delay caused by the piston mechanism. accThat is, the crank acceleration start time estimation unit 106 corrects the ignition timing based on the delay caused by the piston mechanism. Then, the crank acceleration start time estimation unit 106 outputs the estimated crank acceleration start time to the jet flame intensity estimation unit 107 .

[0089] The crank angle information acquisition unit 103 is connected to the crank angle sensor 49 and acquires crank angle information from the crank angle sensor 49. Then, the crank angle information acquisition unit 103 outputs the acquired crank angle information to the rotation variation acquisition unit 104.

[0090] The rotation variation acquisition unit 104 acquires (calculates) the rotation variation amount occurring after the ignition timing based on the crank angle information. In addition, the rotation variation acquisition unit 104 acquires the rotational speed variation amount for each interval between teeth provided on the crankshaft 48. In addition, the rotation variation acquisition unit 104 outputs the acquired rotational speed variation amount to the jet flame intensity estimation unit 107.

[0091] The jet intensity estimation unit 107 estimates the jet intensity based on the crank acceleration start time and the amount of change in the rotation speed, and then outputs the estimated jet intensity to the jet intensity comparison unit 108 .

[0092] The jet intensity comparison unit 108 outputs not only the jet intensity estimated by the jet intensity estimation unit 107 but also the upper limit value and the lower limit value calculated by the jet intensity upper limit value / lower limit value calculation unit 110. The jet intensity comparison unit 108 compares the jet intensity estimated by the jet intensity estimation unit 107 with the upper limit value and the lower limit value calculated by the jet intensity upper limit value / lower limit value calculation unit 110. Then, the jet intensity comparison unit 108 outputs the comparison result to the ignition timing output unit 109. The ignition timing output unit 109 controls the ignition timing based on the comparison result obtained by the jet intensity comparison unit 108.

[0093] In addition, the detailed processing method of each processing unit will be described later.

[0094] 1-4. Examples of jet intensity and fuel consumption and heat loss determined by differences in jet intensity

[0095] Next, refer to FIG. 5A to FIG. 5C , examples of jet flame intensity and the fuel consumption and heat loss determined by the difference in jet flame intensity are explained.

[0096] Figure 5A The figure shows the difference (pressure difference) between the pressure of the sub chamber 8 and the pressure of the main combustion chamber 14a caused by the difference in the jet flame intensity. The vertical axis shows the pressure difference [MPa], and the horizontal axis shows the crank angle. Figure 5B This is a graph showing the relationship between the difference in jet flame intensity and the combustion consumption rate. Figure 5CThis is a diagram showing the relationship between the difference in jet flame intensity and the amount of heat loss from the wall surface of the main combustion chamber 14a. Figure 5B The vertical axis represents the heat consumption rate ISFC [g / kWh], Figure 5C The vertical axis in represents the amount of heat loss [W]. Then, Figure 5B and Figure 5C The horizontal axis in represents the jet flame intensity.

[0097] like Figure 5A As shown in FIG. 1 , the pressure difference at the auxiliary chamber injection hole 8a reaches the maximum value when the auxiliary chamber 8 is ejected into the main combustion chamber 14a. Then, the maximum value of the pressure difference is defined as the jet flame intensity. In addition, the higher the jet flame intensity ejected from the auxiliary chamber 8, the more stable the ignition of the mixed gas. However, when the jet flame intensity is high, as Figure 5C As shown in FIG. 1 , the heat loss of the wall surface of the secondary chamber 8 and the main combustion chamber 14a increases. Figure 5B As shown in FIG. 1 , the fuel consumption rate (fuel consumption amount) increases, and there is a risk that the fuel consumption reduction effect achieved by the auxiliary combustion chamber will decrease.

[0098] Furthermore, when the jet intensity is further increased, the pressure fluctuation of the main combustion chamber 14a increases due to the jet ejection, which may cause knocking. Therefore, the jet intensity needs to be adjusted to an appropriate range while maintaining a balance between combustion stability and heat loss.

[0099] 1-5.1 Changes in pressure, speed, and vibration (acceleration) during a combustion cycle

[0100] Next, the changes in pressure, pressure difference, speed, and vibration (acceleration) of the auxiliary chamber and the main combustion chamber during one combustion cycle are referred to as Figure 6 Provide explanation. Figure 6 (a) represents the pressure of the auxiliary chamber 8, Figure 6 (b) represents the pressure of the main combustion chamber 14a, Figure 6 (c) represents the pressure difference, Figure 6 (d) represents the rotation speed, Figure 6 (e) represents acceleration, that is, the output value of the knock sensor. Figure 6 (a) and Figure 6 The data shown in (b) is obtained by directly plotting the measured waveform. Then, Figure 6 The data shown in (c) is for Figure 6 (a) and Figure 6 The data obtained by filtering the difference between the data shown in (b) and the data after noise reduction processing.

[0101] like Figure 6 As shown in (a), the pressure in the auxiliary chamber 8 reaches the first peak at the top dead center. After that, the pressure rises again due to combustion and reaches the second peak. Then, as shown in Figure 6As shown in (b), the pressure fluctuation of the main combustion chamber 14a is also substantially the same as the pressure fluctuation of the sub chamber 8. Figure 6 (a) and Figure 6 As shown in (b), there is a slight phase difference between the two. Therefore, after the pressure of the auxiliary chamber 8 starts to rise due to combustion, Figure 6 As shown in (c), the pressure difference between the sub chamber 8 and the main combustion chamber 14a reaches a peak. The moment when the pressure difference reaches a peak is the time when the jet flame is ejected from the sub chamber 8 to the main combustion chamber 14a, which is regarded as the start time of the jet flame.

[0102] Figure 6 (d) is a diagram for calculating the engine speed based on the signal detected by the crank angle sensor 49. In this example, as described above, the crank angle sensor 49 with a crank angle detection interval of 6 degrees is used. That is, the crank angle sensor 49 detects the teeth provided on the crankshaft 48 every 6 degrees of crank angle. Then, the crank angle information acquisition unit 103 detects the time difference from the time when the previous tooth was detected, and based on the time difference, the time taken for the crankshaft 48 to advance 6 degrees is calculated, and the engine speed is calculated based on the time.

[0103] like Figure 6 As shown in (d), the engine speed often varies by several + rpm in one combustion cycle. In the compression stroke, the speed decreases because negative torque is generated. In addition, when combustion occurs in the expansion stroke, the piston 18 is pushed by the combustion pressure, so the speed increases from 360 degrees ATDC after the top dead center to 450 degrees ATDC in the middle of the expansion stroke.

[0104] In addition, if Figure 6 As shown in (e), the frequency change of the vibration waveform is observed at the beginning of the flame, but vibration is also observed more frequently outside the combustion period. This is considered to be mainly due to load changes on the engine side and mechanical vibration when the valve is opened and closed. Therefore, these effects can be removed by performing appropriate filtering.

[0105] Here, the relationship between the engine speed and the pressure of the main combustion chamber 14a is described. When the angular velocity ω is obtained by the crank angle sensor 49, the torque generated during combustion, that is, the combustion torque τ comb , according to the friction torque τ fric , inertia torque τ inner 、Load torque τ load The inertia J of the engine rotating system is expressed by the following mathematical formula 1.

[0106] [Mathematical formula 1]

[0107] Jdω=τ comb +τ fric +τinner +τ load

[0108] As shown in equation 1, in order to obtain the combustion torque τ comb , it is necessary to calculate the differential value dω of the angular velocity ω. However, the angular velocity ω measured by the crank angle sensor 49 contains various noises. Therefore, when performing normal differentiation, the noise is emphasized and the accurate torque waveform cannot be reproduced. Therefore, in order to avoid emphasizing the noise due to differentiation, the combustion torque τ can be estimated by using the result obtained by cutting off the high-frequency components contained in the angular velocity ω. comb Hereinafter, the differential value dω of the angular velocity ω is referred to as the rotation speed change rate.

[0109] In addition, the estimated combustion τ comb The friction torque τ is included fric and load torque τ load Therefore, the offset is estimated and corrected by prior fitting. Alternatively, the geometric characteristics of the connecting rod of the four-cylinder engine can be used to offset the offset and obtain the corrected estimated torque τ compensation The corrected estimated torque τ compensation The relationship with the engine rotation speed, that is, the angular velocity ω, is as shown in the following mathematical formula 2.

[0110] [Mathematical formula 2]

[0111] Jdω=τ compensation

[0112] Next, based on the estimated torque τ compensation The pressure in the main combustion chamber 14a, that is, the cylinder pressure P is calculated. comb . Estimated torque τ compensation The cylinder pressure P comb The relationship between is determined by the piston structure, so it is expressed by the following mathematical formula 3. Here, A cyl represents the cross-sectional area of ​​the main combustion chamber 14a, R represents the length of the crank arm, and φ represents the angle between the crank arm and the central axis.

[0113] [Mathematical formula 3]

[0114]

[0115] Then, by combining the above equations 2 and 3, the rotation speed change rate dω and the cylinder pressure P of the main combustion chamber 14a are obtained. comb The relationship is expressed by the following mathematical formula 4.

[0116] [Formula 4]

[0117]

[0118] like Figure 6 As shown in (d), near 370degATDC after the occurrence of the jet flame, the engine speed was observed to rise rapidly between one interval of the crank angle teeth (i.e., 6deg). It was confirmed that the increase in speed occurred in a specific interval in each cycle in the auxiliary combustion chamber. Then, it is believed that the increase in speed was caused by the rapid increase dP / dθ in the pressure of the main combustion chamber 14a caused by the jet flame ignition. Therefore, by estimating the speed change rate dω, the pressure increase dP / dθ of the main combustion chamber 14a can be obtained, and the jet flame intensity can also be estimated.

[0119] 1-6. Calculation method of speed change rate

[0120] Next, refer to Figure 7 A conventional method for estimating the rotation speed change rate dω and a method for estimating the rotation speed change rate dω of this example will be described.

[0121] Figure 7 It is a schematic diagram showing a method of estimating the rotation speed change rate dω. Figure 7 The horizontal axis represents the time, and the vertical axis represents the engine speed (angular velocity ω). Then, Figure 7 The black dots shown in the figure represent the detection signal (crank angle sensor signal) of the crank angle sensor 49. The crank angle sensor signal is a discrete value whose output value is updated at intervals of each tooth. Therefore, the engine speed between teeth is calculated by linearly interpolating the engine speed in the interval before and after the tooth, so it is as follows: Figure 7 The solid lines A1 and A2 are shown in the line graph. Then, the solid line A1 represents the estimation method of this example, and the solid line A2 represents the existing estimation method. In addition, Figure 7 The dotted line shown in represents the actual rotation speed variation.

[0122] In addition, for the acceleration interval (t x+1 -t x ) is calculated by the rotation change acquisition unit 104 based on the following mathematical formula 5.

[0123] [Formula 5]

[0124] Δω={ω_t x+1 -ω_t x}

[0125] First, the conventional method for estimating the rotational speed change rate dω is described. In the conventional estimation method, the rotational speed change rate dω is calculated using only the signal of the crank angle sensor 49. That is, the rotational speed change rate dω is obtained by dividing the rotational speed change Δω by the length of the interval (t x+1 -tx ) to calculate.

[0126] [Mathematical formula 6]

[0127] dω=Δω / (t x+1 -t x )

[0128] Here, the rotation speed change rate dω calculated by the mathematical formula 6 represents the change in the average rotation speed in the crank angle interval of 6 degrees, which is equivalent to Figure 7 However, when trying to capture the rotation speed change caused by the jet flame occurring in a short period of time, the influence becomes smooth and sufficient estimation accuracy cannot be obtained.

[0129] Next, the method for estimating the rotation speed change rate dω of this example is described. In the internal combustion engine control device 20 of this example, the rotation speed change rate dω is calculated using the signal of the acceleration sensor, namely the knock sensor 47, and the crank angle signal of the crank angle sensor 49. First, the knock sensor signal acquisition unit 101 acquires Figure 6 Then, the signal of the knock sensor 47 obtained by the knock sensor signal obtaining unit 101 is processed by the ignition timing estimation unit 105 .

[0130] Here, reference Figure 8 (a) to Figure 8 (c) The signal processing of the knock sensor signal is explained.

[0131] Figure 8 (a) is a waveform showing the output value (knock sensor signal) of the knock sensor 47, Figure 8 (b) is a waveform showing a filter output value obtained by filtering the knock sensor signal. Figure 8 (c) is a graph showing the absolute value of the filter output value.

[0132] The ignition timing estimation unit 105 Figure 8 The knock sensor signal shown in (a) is filtered, thereby obtaining Figure 8 The filter output value shown in (b) of FIG. That is, the ignition timing estimation unit 105 performs a filtering process on the knock sensor signal, thereby extracting the vibration component caused by combustion. In addition, the ignition timing estimation unit 105 performs a bandpass filtering on the knock sensor signal using the bandwidth output from the bandwidth / threshold acquisition unit 102 as a filtering process.

[0133] Figure 8In the example shown in (b), the frequency band of the bandpass filter is set to 1.0kHz to 2.0kHz. When the frequency band includes a frequency band less than 1.0kHz, low-frequency components caused by mechanical vibrations, etc. are superimposed on the filter output value, which is not suitable as a vibration component caused by combustion. Therefore, the lower limit value of the frequency band is set to 1.0kHz. In addition, when the frequency band includes a frequency band greater than 2.0kHz as a frequency band, high-frequency components appear in the filter output value before the start of combustion, which is also an unsuitable waveform for extracting the vibration component caused by combustion. Therefore, the upper limit value of the frequency band is set to 2.0kHz.

[0134] The frequency band, that is, the bandwidth is not limited to the above-mentioned 1.0 kHz to 2.0 kHz, and is appropriately set by the bandwidth / threshold value acquisition unit 102 based on the engine speed information, the engine shape information, and the like as described above.

[0135] In addition, the ignition timing estimation unit 105 calculates Figure 8 The filter output value shown in (b) is converted into an absolute value, and we get Figure 8 Then, the ignition timing estimation unit 105 determines the time when the amplitude of the vibration exceeds the threshold value output from the bandwidth / threshold value acquisition unit 102 as the start time of the flame injection, and obtains the flame injection start time t jet .

[0136] In addition, as described above, the threshold value is appropriately set by the bandwidth / threshold value acquisition unit 102 based on the engine speed.

[0137] In this way, mechanical vibration and high-frequency noise can be appropriately removed by filtering the knock sensor signal output from knock sensor 47. As a result, the ignition timing of the jet flame can be detected with high accuracy.

[0138] Next, the crankshaft acceleration start time estimation unit 106 calculates the crankshaft acceleration start time based on the flame emission start time t jet To estimate the crankshaft acceleration start time t acc As shown in the above equation 4, there is a response delay caused by the inertial mass of the piston mechanism and the crankshaft 48 from the time when the pressure in the main combustion chamber 14a rises until the speed increases. Therefore, the crankshaft acceleration start time estimation unit 106 prepares a plurality of cylinder pressures P of the main combustion chamber 14a that record the start time of the pressure increase caused by the jet flame. comb In addition, the response of the rotational speed change rate dω(θ) to these characteristics is calculated, and the time delay Δt(θ) from the pressure rise in the main combustion chamber 14a to the rotational speed increase is stored as a table in the crankshaft acceleration start time estimation unit 106.

[0139] Then, crankshaft acceleration starts at time t accAccording to the time delay Δt(θ) and the flame start time t jet Calculate according to the following mathematical formula 7.

[0140] [Formula 7]

[0141] t acc =t jet +Δt(θ)

[0142] In this way, by correcting the response delay caused by the piston mechanism using the crankshaft acceleration start timing estimation unit 106, the actual acceleration start timing of the crankshaft 48 can be accurately detected from the ignition timing of the jet flame based on the knock sensor signal.

[0143] Next, the jet intensity estimation unit 107 calculates the rotation speed change rate dω using the rotation speed detected by the crank angle sensor 49, with the acceleration start time of the crankshaft 48 as the starting point. That is, the jet intensity estimation unit 107 calculates the rotation speed change rate dω using the rotation speed change amount Δω calculated in the above equation 5 and the crankshaft acceleration start time t calculated in the equation 7. acc , the rotation speed change rate dω is calculated based on mathematical formula 8.

[0144] [Mathematical formula 8]

[0145] dω=Δω / (t x+1 -t acc )

[0146] Here, Δω calculated by the mathematical formula 8 corresponds to the slope of the solid line A1 shown in FIG5 . As shown in FIG5 , it can be seen that in the method for estimating the rotation speed change rate Δω of this example, the calculation starting point of the rotation speed change rate Δω is changed from the detection time tx of the teeth of the crank angle sensor 49 to the crankshaft acceleration start time tx estimated by the knock sensor 47. acc Furthermore, as shown in FIG. 5 , the solid line A1 obtained by the estimation method of this example can be made closer to the actual rotation speed fluctuation indicated by the dotted line than the solid line A2 obtained by the conventional estimation method.

[0147] In the conventional estimation method, the rotation speed change rate Δω is calculated by always setting the calculation start point to the time tx regardless of the ignition time of the jet flame. As a result, it is not possible to obtain a time resolution finer than the tooth interval detected by the crank angle sensor 49. In contrast, in the estimation method of this example, the crankshaft acceleration start time tx is used as the calculation start point. acc Since the rotation speed change rate Δω is calculated as the calculation start point, the rotation speed change rate Δω can be calculated taking into account the flame start timing that varies depending on the state of the engine.

[0148] 1-7. Calculation method of jet flame intensity

[0149] Next, the method for estimating the jet flame intensity using the rotation speed change rate Δω is described. According to the above equation 4, the term θ is regarded as a constant in a very short time, so the cylinder pressure P of the main combustion chamber 14a is comb , and the rotation speed change rate Δω, are in a proportional relationship as shown in the following mathematical formula 9. In addition, τ shown in the mathematical formula is the torque.

[0150] [Mathematical formula 9]

[0151]

[0152] In an internal combustion engine, generally speaking, when dP / dθ is large and a sudden pressure rise is observed, the cylinder pressure P of the main combustion chamber 14a is comb Therefore, the jet flame intensity I_jet can be calculated indirectly using the rotation speed change rate Δω based on the following mathematical formula 10. pre is the pressure in the secondary combustion chamber.

[0153] [Formula 10]

[0154] I jet =(P pre -P comb )∝dP / dθ∝P comb ∝dω

[0155] In this way, by estimating the rotation speed change rate Δω, the jet intensity I_jet can be estimated.

[0156] Next, the accuracy of the conventional calculation results of the jet flame intensity and the calculation results of the present example is compared. Fig. 9 Provide explanation.

[0157] Fig. 9 This is a diagram showing the accuracy of the conventional estimation result of the jet flame intensity and the estimation result of the jet flame intensity of this example. Fig. 9 The horizontal axis of each figure represents the rotation speed change rate dω. Fig. 9 The vertical axis of each graph in the figure represents the pressure difference between the auxiliary combustion chamber and the main combustion chamber 14a, that is, the jet flame intensity. And, for the maximum value of the pressure difference, the ignition timing is changed to 0 degrees ATC, 3 degrees ATC, 6 degrees ATC, and the average is obtained for 5 consecutive cycles and then plotted.

[0158] like Fig. 9As shown in FIG. 1 , in the conventional estimation result obtained by estimating the rotation speed change rate dω using only the crank angle sensor 49, the correlation coefficient between the rotation speed change rate dω and the jet flame intensity is 0.68. In contrast, in the estimation result of this example obtained by estimating the rotation speed change rate dω using both the crank angle sensor 49 and the knock sensor 47, the correlation coefficient between the rotation speed change rate dω and the jet flame intensity is 0.87. Thus, it can be seen that the accuracy of the estimation result of the jet flame intensity of this example is further improved compared with the conventional estimation result of the jet flame intensity obtained by using only the crank angle sensor 49. That is, by simultaneously using the information of the knock sensor 47, the time resolution of the rotation speed change rate dω can be improved, and the jet flame intensity can be estimated with good accuracy without using a pressure sensor for detecting the pressure of the auxiliary chamber.

[0159] 1-8. Example of corrective control action for jet flame intensity

[0160] Next, an operation example of the correction control of the jet flame intensity in the internal combustion engine control device 20 having the above configuration will be referred to. Figures 10 to 12B Provide explanation.

[0161] Fig.10 This is a flowchart showing the correction control operation of the jet flame intensity.

[0162] like Fig.10 As shown, first, the internal combustion engine control device 20 determines whether the preheating of the engine has been completed (step S11). When the engine is in a cold state, there is a risk that the jet flame intensity is greatly reduced and the combustion on the main combustion chamber 14a side becomes unstable. Therefore, in the process of step S11, if it is determined that the preheating of the engine has not been completed (step S11 is determined to be no), the internal combustion engine control device 20 ends the process without performing the correction process of the jet flame intensity.

[0163] In the process of step S11, when it is determined that the warm-up of the engine has been completed (step S11 is determined as YES), the knock sensor signal acquisition unit 101 acquires knock sensor information from the knock sensor 47 (step S12). Then, the knock sensor signal acquisition unit 101 outputs the acquired knock sensor information (knock sensor signal) to the ignition timing estimation unit 105.

[0164] Next, the ignition timing estimation unit 105 performs a filtering process on the knock sensor signal to extract the combustion component (step S13). In the process of step S13, the ignition timing estimation unit 105 performs a bandpass filtering on the knock sensor signal using the bandwidth output from the bandwidth / threshold acquisition unit 102. Figure 8 The knock sensor signal shown in (a) is obtained Figure 8 The filter output value shown in (b).

[0165] Next, the ignition timing estimation unit 105 estimates the ignition timing t of the jet flame based on the filter output value obtained by extracting the combustion component. jet (Step S14) That is, the ignition timing estimation unit 105 converts the filter output value into an absolute value as described above to obtain Figure 8 Then, the ignition timing estimation unit 105 estimates the time when the value exceeds the threshold value output from the bandwidth / threshold value acquisition unit 102 as the ignition timing t of the jet flame. jet In addition, the ignition timing estimation unit 105 calculates the ignition timing t of the jet flame. jet The signal is output to the crank acceleration start time estimation unit 106 .

[0166] Next, the crank angle information acquisition unit 103 acquires crank angle information from the crank angle sensor 49 (step S15). Then, the crank angle information acquisition unit 103 outputs the acquired crank angle information to the rotation change acquisition unit 104. In addition, the rotation change acquisition unit 104 calculates the rotation speed change amount Δω according to equation 5, and outputs the calculated rotation speed change amount Δω to the jet flame intensity estimation unit 107.

[0167] In addition, the crankshaft acceleration start time estimation unit 106 is based on the flame emission start time t jet Using equation 6, the crankshaft acceleration start time (time) t is estimated. acc (Step 16). Then, the crankshaft acceleration start time estimation unit 106 calculates the crankshaft acceleration start time t acc The result is output to the flame intensity estimation unit 107 .

[0168] Next, the jet flame intensity estimation unit 107 calculates the jet flame intensity based on the rotation speed change Δω and the crankshaft acceleration start time t acc , according to the acceleration start time t acc The jet intensity I_jet is estimated from the rotation speed change rate dω that occurs thereafter (step S17). That is, the jet intensity estimation unit 107 calculates the rotation speed change rate dω based on equation 8, and estimates the rotation speed change rate dω as the jet intensity I_jet. Then, the jet intensity estimation unit 107 outputs the estimated jet intensity I_jet to the jet intensity comparison unit 108.

[0169] The jet intensity comparison unit 108 determines whether the jet intensity I_jet is greater than the lower limit value Imin output from the jet intensity upper limit value / lower limit value calculation unit 110 (step S18). In the process of step S18, if it is determined that the jet intensity I_jet is less than the lower limit value Imin (step S18 determines that it is not), the internal combustion engine control device 20 performs a jet intensity increase process (step S19). When the jet intensity increase process of step S19 is completed, the process returns to step S12 again.

[0170] In the process of step S18, if it is determined that the jet intensity I_jet is greater than the lower limit value Imin (step S18 determines yes), the process proceeds to step S20. In the process of step S20, the jet intensity comparison unit 108 determines whether the jet intensity I_jet is greater than the upper limit value Imax output from the jet intensity upper limit value / lower limit value calculation unit 110.

[0171] In the process of step S20, if it is determined that the jet intensity I_jet is greater than the upper limit value Imax (step S20: No), the internal combustion engine control device 20 performs a process of reducing the jet intensity (step S21). When the process of increasing the jet intensity of step S21 is completed, the process returns to step S12.

[0172] In the process of step S20, when it is determined that the jet intensity I_jet is less than or equal to the upper limit value Imax (YES in step S20), the internal combustion engine control device 20 determines that the jet intensity I_jet is within an appropriate range and ends the control.

[0173] Next, refer to FIG. 11A to FIG. 12B An example of the increase / decrease process of the jet flame intensity shown in step S19 and step S20 will be described.

[0174] Fig.11A 1 is a diagram showing an example of the increase / decrease process of the jet flame intensity, wherein the horizontal axis represents the jet flame intensity and the vertical axis represents the ignition timing.

[0175] like Fig.11A As shown, the stronger the jet intensity I_jet is, the more the ignition timing is corrected in the retarding direction by the ignition timing output unit 109. By retarding the ignition timing, the combustion center of gravity is retarded, and the combustion temperature in the sub chamber 8 is reduced. Thus, the jet intensity I_jet can be reduced.

[0176] When the jet intensity I_jet is weak, the ignition timing output unit 109 corrects the ignition timing to advance. By advancing the ignition timing, the combustion center of gravity advances, and the combustion temperature in the sub chamber 8 rises. Thus, the jet intensity I_jet can be increased.

[0177] Fig. 11B 1 is a diagram showing another example of the increase / decrease process of the jet flame intensity. The horizontal axis represents the jet flame intensity, and the vertical axis represents the EGR rate target value [%].

[0178] like Fig. 11B As shown, the internal combustion engine control device 20 controls the EGR rate target value in accordance with the jet flame intensity I_jet. That is, the stronger the jet flame intensity I_jet is, the higher the EGR rate target value is. By increasing the EGR rate, the dilution rate of the mixed gas is increased. As a result, the combustion temperature in the sub chamber 8 is reduced, and the jet flame intensity I_jet can be reduced.

[0179] In addition, when the jet intensity I_jet is weak, the EGR rate target value is corrected to be lowered. By lowering the EGR rate, the dilution rate of the air-fuel mixture is reduced. As a result, the combustion temperature in the sub chamber 8 rises, and the jet intensity I_jet can be increased.

[0180] Fig. 12A 2 is a diagram showing another example of the increase / decrease process of the jet flame intensity. The horizontal axis represents the jet flame intensity, and the vertical axis represents the A / F target value.

[0181] like Fig. 12A As shown, the internal combustion engine control device 20 controls the A / F target value in accordance with the jet flame intensity I_jet. That is, the A / F target value is corrected in such a way that the stronger the jet flame intensity I_jet is, the higher the A / F target value is. By increasing the A / F, the dilution rate of the mixed gas is increased. As a result, the combustion temperature in the sub chamber 8 is reduced, and the jet flame intensity I_jet can be reduced.

[0182] In addition, when the jet intensity I_jet is weak, the A / F target value is corrected to be lowered. By reducing the A / F, the dilution rate of the mixed gas is reduced. As a result, the combustion temperature in the sub chamber 8 rises, and the jet intensity I_jet can be increased.

[0183] Fig. 12B This is a diagram showing another example of the increase / decrease process of the jet flame intensity. The horizontal axis represents the jet flame intensity, and the vertical axis represents the ignition energy [mJ].

[0184] like Fig. 12B As shown, the internal combustion engine control device 20 controls the ignition energy in accordance with the jet flame intensity I_jet. That is, the stronger the jet flame intensity I_jet is, the more the ignition energy is reduced. By reducing the ignition energy, the ignition delay period increases, and the combustion center of gravity is delayed, and the combustion temperature in the sub chamber 8 is reduced, just like when the ignition timing is delayed. As a result, the jet flame intensity I_jet can be reduced.

[0185] In addition, when the jet flame intensity I_jet is weak, the ignition energy is increased to correct it. By increasing the ignition energy, the ignition delay period is reduced, and the combustion center of gravity is advanced, and the combustion temperature in the sub chamber 8 increases, similar to when the ignition timing is advanced. As a result, the jet flame intensity I_jet can be increased.

[0186] In addition, the increase / decrease process of the jet flame intensity is not limited to the above-mentioned example, and various other increase / decrease methods can be applied.

[0187] 2. Second Embodiment Example

[0188] Next, refer to Figures 13 to 15 An internal combustion engine control device according to a second embodiment will be described.

[0189] Fig.13 This is a block diagram showing a configuration of a jet flame intensity estimation process of an internal combustion engine control device according to the second embodiment. Fig.14 This is a map showing the knock sensor amplitude confidence ratio when estimating the jet flame intensity under each engine operating condition. Fig.15 It is a diagram showing a method of estimating the jet intensity by the second jet intensity estimating unit of the internal combustion engine control device of the second embodiment. Components common to the internal combustion engine control device 20 of the first embodiment are denoted by the same reference numerals and repeated descriptions are omitted.

[0190] like Fig.13 As shown in FIG. 1 , the internal combustion engine control device 20B includes a knock sensor signal acquisition unit 101, a bandwidth / threshold value acquisition unit 102, a crank angle information acquisition unit 103, a rotation variation acquisition unit 104, an ignition timing estimation unit 105, and a crankshaft acceleration start timing estimation unit 106. In addition, the internal combustion engine control device 20B includes a jet flame intensity comparison unit 108 and an ignition timing output unit 109. The configurations of these processing units are the same as those of the processing units in the first embodiment, and thus their descriptions are omitted.

[0191] Furthermore, the internal combustion engine control device 20B includes a first jet intensity estimating unit 207A, a second jet intensity estimating unit 207B, a jet intensity selecting unit 201, a confidence rate β calculating unit 202, and a jet intensity upper limit value / lower limit value calculating unit 210. The configuration of the first jet intensity estimating unit 207A is the same as that of the jet intensity estimating unit 107 of the first embodiment, and thus the description thereof is omitted. In addition, the first jet intensity estimating unit 207A outputs the estimated first jet intensity to the jet intensity selecting unit 201.

[0192] The second jet intensity estimating unit 207B is connected to the knock sensor 47 and acquires a knock sensor signal from the knock sensor 47. The second jet intensity estimating unit 207B estimates the second jet intensity based on the knock sensor signal. In addition, the method of estimating the second jet intensity by the second jet intensity estimating unit 207B will be described later. Then, the second jet intensity estimating unit 207B outputs the estimated second jet intensity to the jet intensity selecting unit 201.

[0193] The jet intensity selection unit 201 is connected to the confidence rate β calculation unit 202, and the confidence rate β is output from the confidence rate β calculation unit 202. Then, the jet intensity selection unit 201 selects a jet intensity used as an index between the first jet intensity and the second jet intensity according to the confidence rate β. The jet intensity selection unit 201 outputs the selected jet intensity to the jet intensity comparison unit 108.

[0194] For example, when the confidence rate β is less than a predetermined value, the jet intensity selection unit 201 determines that the first jet intensity estimated by the first jet intensity estimation unit 207A has high reliability and selects the first jet intensity. When the confidence rate β is greater than a predetermined value, the jet intensity selection unit 201 determines that the second jet intensity estimated by the second jet intensity estimation unit 207B has high reliability and selects the second jet intensity.

[0195] The confidence rate β calculation unit 202 is connected to the accelerator pedal opening sensor 12. Then, the confidence rate β calculation unit 202 receives the throttle valve opening and engine speed information from the accelerator pedal opening sensor 12. Fig.14 The map shown is a map showing the knock sensor amplitude confidence ratio β when estimating the jet intensity under each engine operating condition. Fig.14 The horizontal axis in FIG. 2 represents the engine speed [rpm], and the vertical axis represents the engine load IMEP [rpm]. The confidence rate β calculation unit 202 calculates the confidence rate β based on the engine operating conditions. Fig.14 The confidence factor β is calculated from the map shown and is output to the jet intensity selection unit 201 .

[0196] The jet intensity upper limit value / lower limit value calculation unit 210 of the second embodiment calculates the upper limit value and the lower limit value corresponding to the first jet intensity estimation unit 207A and the second jet intensity estimation unit 207B. That is, the jet intensity upper limit value / lower limit value calculation unit 210 calculates the upper limit value and the lower limit value according to the jet intensity selected by the jet intensity selection unit 201. Then, the jet intensity upper limit value / lower limit value calculation unit 210 outputs the calculated upper limit value and the lower limit value to the jet intensity comparison unit 108.

[0197] Next, the method for estimating the second jet flame intensity by the second jet flame intensity estimation unit 207B is referred to as follows: Fig.15 Provide explanation.

[0198] Here, in the first jet intensity estimation unit 207A, as described above, the knock sensor signal is used only in the estimation of the ignition timing of the jet, and the amplitude information of the knock sensor signal is not used. However, the amplitude information of the knock sensor signal also includes the vibration at the time of ignition. Therefore, at low speeds when the mechanical vibration of the engine is relatively small, and at low loads when the engine speed changes little and the detection accuracy of the rotation change (rotation change amount Δω) of the crank angle sensor 49 deteriorates, the amplitude information of the knock sensor signal can be used for the estimation of the jet intensity.

[0199] like Fig.15 (a) to Fig.15As shown in (c) of FIG. 1 , the second jet intensity estimation unit 207B performs filtering processing on the knock sensor signal, converts the filter output value into an absolute value, and obtains the amplitude of the vibration, similarly to the ignition timing estimation unit 105. Then, the second jet intensity estimation unit 207B performs filtering processing on the knock sensor signal, converts the filter output value into an absolute value, and obtains the amplitude of the vibration. Fig.15 As shown in (c), the maximum amplitude of the knock sensor signal in the range after the ignition timing and before the exhaust valve opening period is estimated as the second jet flame intensity Ij et-kocksensor .

[0200] The other configurations are the same as those of the internal combustion engine control device 20 of the first embodiment, and thus descriptions thereof are omitted. The internal combustion engine control device 20B having such a configuration can also achieve the same operational effects as those of the internal combustion engine control device 20 of the first embodiment.

[0201] In addition, according to the internal combustion engine control device 20B of the second embodiment, the reliability of each sensor is set according to the operating state, and the sensor information used when estimating the jet intensity is determined. This can maximize the performance of each sensor provided in the internal combustion engine 100 and improve the estimation accuracy of the jet intensity.

[0202] In addition, in the internal combustion engine control device 20B of the second embodiment, an example is described in which the first jet intensity estimated by the first jet intensity estimating unit 207A and the second jet intensity estimated by the second jet intensity estimating unit 207B are switched by using the confidence rate β as a threshold value, but the present invention is not limited to this. For example, a value obtained by weighting and averaging the jet intensities estimated by the jet intensity estimating units 207A and 207B may be used as the jet intensity. Furthermore, the estimated error of the jet intensity estimated based on the specifications of the knock sensor 47 and the crank angle sensor 49 may be calculated in advance as the prior error distribution σ, and the prior error distribution σ may be used for the calculation of the confidence rate β.

[0203] 3. Third embodiment example

[0204] Next, the internal combustion engine control device according to the third embodiment is referred to as Fig.16 Provide explanation.

[0205] Fig.16 This is a graph showing the correlation between the jet flame intensity and the initial combustion period. The horizontal axis represents the initial combustion period (ignition timing - MFB02) obtained by the combustion analysis device based on the cylinder pressure of the main combustion chamber 14a. In addition, the vertical axis represents the jet flame intensity (the maximum value of the pressure difference between the auxiliary combustion chamber and the main combustion chamber).

[0206] like Fig.16As shown, it can be seen that the initial combustion period has a high correlation with the jet flame intensity. That is, the method of estimating the jet flame intensity can be replaced by the method of estimating the initial combustion speed in the jet flame ignition. Therefore, in the internal combustion engine control device of the third embodiment, not only the jet flame intensity is estimated, but also the initial combustion period is estimated. Thus, by estimating the jet flame intensity, the initial combustion period can be estimated, which is applied to various engine controls.

[0207] 4. Fourth Implementation Example

[0208] Next, the internal combustion engine control device according to the fourth embodiment is referred to as Fig.17 Provide explanation.

[0209] Fig.17 This is a diagram showing changes in the in-cylinder pressure and torque of the main combustion chamber 14a in one combustion cycle. The vertical axis represents torque [Nm] and in-cylinder pressure [MPa], and the horizontal axis represents the rotation angle of the crankshaft 48 in one combustion cycle.

[0210] In the internal combustion engine control device 20 of the first embodiment, the rotation speed change rate dω is estimated as the jet flame intensity. Fig.17 As shown, when the acceleration start timing of the crankshaft 48 is close to the top dead center, the combustion pressure is hardly converted into torque, and the torque value becomes 0. As a result, there is a risk that the pressure fluctuation cannot be detected as the rotation fluctuation.

[0211] Therefore, in the internal combustion engine control device of the fourth embodiment, the jet intensity estimation unit 107 estimates the rotation speed change rate dω using equation 8. Then, the jet intensity estimation unit 107 calculates the cylinder pressure P of the main combustion chamber 14a taking into account the correlation of the pressure-torque conversion performed by the piston mechanism based on equation 4. comb Alternatively, use Formula 4 to calculate the cylinder pressure P at each crank angle: comb The slope dP / dθ is calculated based on the result, and the jet flame intensity is estimated from it.

[0212] Thus, according to the internal combustion engine control device of the fourth embodiment, it is possible to prevent the jet flame intensity from being inaccurately detected due to the singular point of the piston mechanism near the top dead center, and improve the estimation accuracy of the jet flame intensity. In addition, the jet flame intensity estimation unit 107 of the fourth embodiment can calculate the cylinder pressure P using the mathematical formula 4 only when it is determined that the occurrence time of the jet flame is close to the top dead center. comb Or its slope dP / dθ. Thus, it is possible to reduce the calculation load.

[0213] 5. Fifth embodiment example

[0214] Next, refer to Figure 18 to Figure 19 An internal combustion engine control device according to a fifth embodiment will be described.

[0215] The internal combustion engine control device 20 of the first embodiment detects the end timing of the jet flame based on the crank information of the crank angle sensor 49. In contrast, the internal combustion engine control device of the fifth embodiment detects the end timing of the jet flame based on the signal of the ignition coil 16.

[0216] Fig.18 : is a diagram showing an example of the changing state of the jet flame and the pressure difference ΔP. Fig.18 In the lower part of FIG. 1 , a graph of the pressure difference ΔP corresponding to the crank angle is shown. In addition, the graph of the pressure difference ΔP is attached to Fig.18 The reference numerals of the explanatory diagrams (a) to (c) showing the change of the jet flame are shown in the upper part of FIG. In addition, in the figure, the auxiliary combustion chamber is abbreviated as "auxiliary chamber", and the main combustion chamber 14a is abbreviated as "main chamber". In addition, the arrows shown in the explanatory diagrams (a) to (c) indicate the propagation direction of the flame.

[0217] like Fig.18 As shown in the explanatory diagram (a), the piston 18 is rising and ignition is performed by the spark plug 17. Then, a flame is formed in the auxiliary combustion chamber and the flame propagates in the auxiliary combustion chamber. At this time, according to Fig.18 As can be seen from the lower graph, the pressure difference ΔP is a positive value.

[0218] Then, if Fig.18 As shown in the illustration (b), the piston 18 passes the top dead center and begins to descend, and the flame is ejected from the auxiliary combustion chamber to the main combustion chamber 14a. Fig.18 From the lower graph, it can be seen that the pressure difference ΔP also shows a positive value.

[0219] Then, if Fig.18 As shown in the explanatory diagram (c), due to the jet flame ejected into the main combustion chamber 14a, the mixed gas in the main combustion chamber 14a is burned, and the piston 18 descends. Then, the pressure in the auxiliary combustion chamber becomes negative pressure. At this time, according to Fig.18 As can be seen from the lower graph of FIG. 1 , the pressure difference ΔP is a negative value. Therefore, the flame returns from the main combustion chamber 14a to the auxiliary combustion chamber. In addition, the occurrence of the return indicates that the ignition of the mixed gas in the main combustion chamber 14a by the jet flame has been completed. Therefore, at the time of detecting the return, that is, the jet flame end time t burn , the calculation of the rotation speed change rate dω is interrupted. Therefore, the rotation speed change rate dω is calculated by the following mathematical formula 11.

[0220] [Mathematical formula 11]

[0221] dω=Δω / (t burn -t acc )

[0222] That is, the jet flame intensity estimation unit of the fifth embodiment is based on the acceleration start time t acc Or the flame start time t jet Until the flame ends burn The speed change Δω between the two is used to calculate the speed change rate dω.

[0223] like Fig.18 As shown in the explanatory diagrams (b) to (c) of FIG. 1 , the flow of the air-fuel mixture in the auxiliary combustion chamber changes greatly. Then, the turbulence between the electrodes of the spark plug 17 changes greatly, and the resistance Rsp between the electrodes also changes.

[0224] Fig.18 The timing of return shown in the explanatory diagram (c) is within the range of crank angle 0 to 20 [deg.ATDC]. In addition, if it is delayed compared to the range of crank angle 0 to 20 [deg.ATDC], the flame will not return from the main combustion chamber 14a to the auxiliary combustion chamber because the expansion stroke has already begun. On the other hand, if it is advanced compared to the range of crank angle 0 to 20 [deg.ATDC], the pressure in the engine 100 becomes too high, so it is a condition outside the application range.

[0225] Next, refer to Fig.19 A method of detecting the return timing will be described.

[0226] Fig.19 1 is a first control timing chart for explaining the detection of combustion timing. Fig.19 The changes of ignition signal and discharge secondary current are shown in sequence from the top. Figure 8 The horizontal axis represents time.

[0227] The internal combustion engine control device of the fifth embodiment outputs an ignition signal to the ignition coil 16. The pulse width of the ignition signal is expressed as a charging period tc, and the primary coil is energized during the charging period tc.

[0228] After the charging period tc, the internal combustion engine control device controls the start of discharge of the spark plug 17 by lowering the ignition signal. In the spark plug 17, discharge occurs between the electrodes during the discharge period td. The internal combustion engine control device detects the current change timing of the discharge secondary current based on the value of the discharge secondary current during the discharge between the electrodes fed back from the spark plug 17. During the return period of the flame expressed by the crank angle 0 to 20 [deg.ATDC], the flame returns from the main combustion chamber 14 to the sub-chamber 8, so the value of the discharge secondary current changes dramatically. Then, the internal combustion engine control device detects the moment when the value of the discharge secondary current changes dramatically as the return time td. burn .

[0229] As described above, the internal combustion engine control device of the fifth embodiment can accurately detect both the start and end times of the jet flame, and can make the rotation speed change rate dω close to the actual rotation speed fluctuation. As a result, the estimation accuracy of the jet flame intensity can be improved.

[0230] 6. Modifications of Internal Combustion Engines

[0231] Next, refer to Fig. 20 Modifications of the internal combustion engine will be described.

[0232] Fig. 20 This is a schematic structural diagram showing an enlarged structure of the periphery of a sub chamber of an internal combustion engine according to a modified example.

[0233] Figure 1 The internal combustion engine 100 shown is a passive type internal combustion engine in which the injector 13 is provided on the side of the cylinder 14 and only the spark plug 17 is provided in the sub chamber 8. Figure 1 Passive type shown.

[0234] As an internal combustion engine to which the internal combustion engine control device of the present invention is applied, for example, Fig. 20 The active type internal combustion engine shown in the figure has an injector 13C disposed in the sub chamber 8. In addition, the injector 13C directly injects fuel into the sub chamber 8. In the case of the active type, the air-fuel ratio in the sub chamber 8 can be controlled so that the ignition property is good by the air supplied from the main combustion chamber 14a side through the sub chamber injection hole 8a and the fuel supplied from the injector 13C. As a result, the combustion stability can be improved.

[0235] In addition, 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 gist of the invention described in the claims.

[0236] For example, the above-mentioned embodiments describe the structure of the device and system in detail and specifically in order to explain the present invention in an easy-to-understand manner, and are not limited to all the structures that must be described. In addition, a part of the structure of the embodiment described here can be replaced with the structure of other embodiments, and the structure of other embodiments can be added to the structure of a certain embodiment. In addition, for a part of the structure of each embodiment, other structures can be added, deleted, or replaced.

[0237] In addition, the control lines and information lines are shown as necessary for explanation, and not all the control lines and information lines on the product are necessarily shown. In fact, it can be considered that almost all structures are connected to each other.

[0238] Description of Reference Numerals

[0239] 2... electronically controlled throttle valve, 3... intake pressure sensor, 4... supercharger, 5... variable valve, 6... intake pipe, 8... sub-chamber, 8a... sub-chamber injection hole, 13, 13B, 13C... injector, 14... cylinder, 14a... main combustion chamber, 15... exhaust pipe, 16... ignition coil, 17... spark plug, 18... piston, 20, 20B... ECU (internal combustion engine control unit), 21... input circuit, 22... input / output port, 23a... CPU, 23b... ROM, 23c... RAM, 24... ignition control unit, 47... knock sensor, 48... crankshaft, 49... crank angle sensor, 100... engine Engine (internal combustion engine), 101...knock sensor signal acquisition unit, 102...bandwidth / threshold value acquisition unit, 103...crank angle information acquisition unit, 104...rotational variation acquisition unit, 105...ignition timing estimation unit, 106...crankshaft acceleration start timing estimation unit (ignition timing correction unit), 107...jet flame intensity estimation unit, 108...jet flame intensity comparison unit, 109...ignition timing output unit, 110, 210...jet flame intensity upper limit value / lower limit value calculation unit, 201...jet flame intensity selection unit, 202...confidence rate β calculation unit, 207A...first jet flame intensity estimation unit, 207B...second jet flame intensity estimation unit.

Claims

1. An internal combustion engine control device for controlling an internal combustion engine, wherein the internal combustion engine includes a main combustion chamber facing a piston, a secondary combustion chamber communicating with the main combustion chamber, a spark plug installed inside the secondary combustion chamber, a crankshaft connected to the piston, a crank angle sensor for detecting a rotation angle of the crankshaft, a cylinder forming the main combustion chamber, and a knock sensor for detecting vibration of the cylinder, wherein the internal combustion engine control device is characterized in that it includes: an ignition timing estimation unit that estimates an ignition timing at which the jet flame injected from the auxiliary combustion chamber ignites the mixed gas in the main combustion chamber based on a knock sensor signal detected by the knock sensor; a crank angle information acquiring unit for acquiring crank angle information detected by the crank angle sensor; a rotation variation acquisition unit for calculating a rotation speed variation amount generated after the ignition timing based on the crank angle information; and A jet flame intensity estimation unit calculates a rate of change in the rotation speed occurring after the ignition timing based on the rotation speed change amount calculated by the rotation variation acquisition unit and the ignition timing estimated by the ignition timing estimation unit to estimate the jet flame intensity.

2. The internal combustion engine control device according to claim 1, characterized in that: The ignition timing estimation unit performs a filter process on the knock sensor signal, and estimates the ignition timing from a filter output value subjected to the filter process.

3. The internal combustion engine control device according to claim 1, characterized in that: The system further includes an ignition timing correction unit that corrects the ignition timing estimated by the ignition timing estimation unit based on a piston mechanism. The jet flame intensity estimation unit calculates the rotation speed change rate based on the ignition timing corrected by the ignition timing correction unit and the rotation speed change amount to estimate the jet flame intensity.

4. The internal combustion engine control device according to claim 1, characterized in that include: a first jet flame intensity estimation unit that calculates the rotation speed change rate and estimates a first jet flame intensity based on the rotation speed change amount and the ignition timing; and A second jet intensity estimating unit estimates a second jet intensity based on the knock sensor signal.

5. The internal combustion engine control device according to claim 4, characterized in that: The system further includes a jet flame intensity selection unit configured to select a jet flame intensity to be used as an indicator from among the first jet flame intensity and the second jet flame intensity.

6. The internal combustion engine control device according to claim 1, characterized in that have: The jet intensity estimation unit estimates the in-cylinder pressure of the main combustion chamber from the rotation speed change rate, and estimates the jet intensity from the in-cylinder pressure.

7. The internal combustion engine control device according to claim 1, characterized in that: The jet flame intensity estimating unit, The flame end time is detected based on a signal from an ignition coil that controls the ignition operation of the spark plug. The rotation speed change rate is calculated based on the rotation speed change amount during a period from the ignition timing to the flame end timing.

8. The internal combustion engine control device according to claim 1, characterized in that: Based on the jet flame intensity estimated by the jet flame intensity estimation unit, one or more parameters of ignition timing, fuel injection amount, ignition energy, and EGR valve opening are corrected.

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