Internal combustion engine control device and internal combustion engine control method

Abstract

Provided is an internal combustion engine control device including a rotational speed conversion section, a maximum rotational speed detection section, a center of combustion estimation section, and a deviation calculation section. The deviation calculation section calculates a deviation between an adjusted ignition timing in an adjusted cylinder and an ignition timing in a correction target cylinder that is the same as or different from the adjusted cylinder among a plurality of cylinders. Then, the center of combustion estimation section changes a relationship between a maximum value of a rotational speed used when estimating a center of combustion of the correction target cylinder and the center of combustion, based on the deviation calculated by the deviation calculation section.

Description

Technical Field

[0001] This invention relates to an internal combustion engine control device and an internal combustion engine control method. Background Technology

[0002] Due to the tightening of emission and fuel consumption restrictions in recent years, there is a demand for lower emissions and higher efficiency in gasoline engines. In this context, combustion control techniques are known that calculate the state of the combustion chamber of an engine (also called an internal combustion engine) and control the engine based on these calculations. By appropriately controlling ignition and injection times in accordance with the calculated combustion state, it is possible to improve engine thermal efficiency or reduce harmful gas emissions. An example of such a combustion state calculation technique is disclosed in Patent Document 1.

[0003] Patent document 1 describes "a unit for calculating the rotational acceleration of an engine and a unit for calculating the combustion state in the combustion chamber based on the rotational acceleration". Specifically, it describes the correlation between the rotational position where the rotational acceleration reaches an extreme value and the combustion phase, and calculates the combustion phase based on the rotational position where the rotational acceleration reaches an extreme value detected by a rotation angle sensor.

[0004] Examples of actual phenomena involving engines that relate to the technology disclosed in Patent Document 1 will be explained.

[0005] Figure 16A and Figure 16B It is a graph showing the relationship between the cylinder pressure corresponding to the crank angle and the engine speed. Figure 16A and Figure 16B In the example shown, instead of the rotational acceleration disclosed in Patent Document 1, the rotational speed is described as a parameter.

[0006] Figure 16A An example curve showing the relationship between crank angle and cylinder pressure is shown. The curve shows the ignition timing and the moment of MFB50. After the air-fuel mixture is ignited at the specified timing, combustion begins, the cylinder pressure rises, and combustion ends after the combustion phase where the burned mass fraction of the mixture reaches 50% (hereinafter referred to as "MFB (Mass Fraction Burned) 50"). This combustion phase affects the crankshaft's rotational position where the rotational speed reaches its extreme (maximum value) (hereinafter referred to as "θω_MAX"). In the following explanation, the combustion phase where the burned mass fraction reaches 50% is referred to as the "combustion center of gravity". Then, Figure 16A The curve shown is used as an example of the second approximation curve for obtaining the ignition time based on the combustion center of gravity approximation.

[0007] Figure 16BAn example curve showing the relationship between crank angle and rotational speed is shown. The curve shows the moment when the rotational speed reaches its maximum value, θω_MAX. Figure 16B The curve shown is used as an example of the first approximate curve for obtaining the rotational speed corresponding to the crank angle.

[0008] Figure 17 This is a graph showing the relationship between θω_MAX and MFB50.

[0009] To use Figure 16A and Figure 16B The curves shown represent physical phenomena as background, in Figure 17 The image shows an example of a high correlation between θω_MAX and MFB50. Therefore, by using a model based on... Figure 17 The relationship between θω_MAX and MFB50 shown generates a correction curve, and the internal combustion engine control unit can calculate MFB50 based on θω_MAX.

[0010] Such a combustion control technique using a calibration curve is disclosed, for example, in Patent Document 2. Patent Document 2 describes a method for calculating MFB50 based on θ_MAX detected by a crank angle sensor using a calibration curve, and controlling the ignition timing based on the difference between the calculated MFB50 and the target MFB50.

[0011] Existing technical documents

[0012] Patent documents

[0013] Patent Document 1: Japanese Patent Application Publication No. 2017-150393

[0014] Patent Document 2: Japanese Patent Application Publication No. 2020-190234 Summary of the Invention

[0015] The problem that the invention aims to solve

[0016] Furthermore, by setting appropriate ignition timings for each cylinder, the combustion efficiency of an internal combustion engine can be improved. Therefore, in recent years, individual cylinder ignition timing control, which specifies an inherent ignition timing for each cylinder, has been used. However, in the case of individual cylinder ignition timing control, due to variations in the MFB50 of the cylinder whose ignition timing is controlled, the combustion torque and crankshaft angular velocity also change.

[0017] Furthermore, an internal combustion engine has multiple cylinders connected by a crankshaft. Therefore, because the cylinder controlling the ignition timing of each cylinder affects the phase of θω_MAX of the other cylinders, the correlation between θω_MAX of each cylinder and MFB50 changes. Consequently, the correlation between θω_MAX of each cylinder and MFB50 changes, thus… Figure 17Errors are generated in the calibration curve shown, reducing the accuracy of the calculated combustion center of gravity, i.e., MFB50.

[0018] The purpose of this invention is to address the aforementioned problems by providing an internal combustion engine control device and method capable of accurately calculating the combustion center of gravity.

[0019] Methods for solving problems

[0020] To address the aforementioned issues, for example, the structure described in the claims may be employed.

[0021] This application includes various means to solve the aforementioned problems. For example, the internal combustion engine control device of the present invention is an internal combustion engine control device that individually adjusts and controls the ignition timing of multiple cylinders. It includes a speed conversion unit, a maximum speed detection unit, a combustion center of gravity calculation unit, and a deviation calculation unit. The speed conversion unit converts the crank angle of the crankshaft connected to the cylinders into the speed of the internal combustion engine. The maximum speed detection unit detects the maximum value of the speed converted by the speed conversion unit. The combustion center of gravity calculation unit calculates the combustion center of gravity of the cylinder based on the maximum speed. The deviation calculation unit calculates the deviation between the adjusted ignition timing of the adjusted cylinder and the ignition timing of the target cylinder (which may be the same as or different from the adjusted cylinder). Then, based on the deviation calculated by the deviation calculation unit, the combustion center of gravity calculation unit changes the relationship between the maximum speed and the combustion center of gravity used when calculating the combustion center of gravity of the target cylinder.

[0022] In addition, the internal combustion engine control method of the present invention is an internal combustion engine control method that individually adjusts and controls the ignition timing of multiple cylinders, and includes the processes shown in (1) to (4) below.

[0023] (1) Processing of converting the crank angle of the crankshaft connected to the cylinder into the speed of the internal combustion engine.

[0024] (2) Processing to detect the maximum value of the converted rotation speed.

[0025] (3) The process of calculating the deviation between the adjusted ignition time of the cylinder after adjusting the ignition time and the ignition time of the correction target cylinder that is the same as or different from the adjusted cylinder in multiple cylinders.

[0026] (4) Based on the deviation, change the relationship between the maximum speed used when calculating the combustion center of gravity of the target cylinder and the combustion center of gravity, and calculate the combustion center of gravity of the target cylinder.

[0027] Invention Effects

[0028] Based on the internal combustion engine control device and method described above, the combustion center of gravity can be calculated with high accuracy.

[0029] Other issues, structures, and effects not described above will be explained through the following description of the implementation methods. Attached Figure Description

[0030] Figure 1 This is a schematic structural diagram showing the structure of the internal combustion engine on which the internal combustion engine control device of the embodiment example is mounted.

[0031] Figure 2 This is a block diagram illustrating the control system of the internal combustion engine control device in the embodiment example.

[0032] Figure 3 This is a block diagram illustrating the structure of the combustion detection section of an internal combustion engine control device according to an embodiment example.

[0033] Figure 4 This is an explanatory diagram representing the average ignition time control as an existing ignition time control method.

[0034] Figure 5 This is a diagram illustrating an example of existing average ignition time control.

[0035] Figure 6 This is an explanatory diagram illustrating the ignition timing control of each cylinder in the internal combustion engine control device of the embodiment example.

[0036] Figure 7 This is a diagram illustrating a control example of controlling the ignition timing of each cylinder in an internal combustion engine control device according to an embodiment example.

[0037] Figure 8 This is a diagram illustrating a control example of controlling the ignition timing of each cylinder in an internal combustion engine control device according to an embodiment example.

[0038] Figure 9 This is a graph showing the calculated MFB50 under the condition of using an inappropriate correction curve.

[0039] Figure 10 This is a diagram illustrating a control example of controlling the ignition timing of each cylinder in an internal combustion engine control device according to an embodiment example.

[0040] Figure 11 This is an explanatory diagram showing an outline of the correction process for the calibration curve in the internal combustion engine control device of the embodiment example.

[0041] Figure 12 This is a graph showing the calculated MFB50 when calculated using the corrected calibration curve.

[0042] Figure 13 This is a flowchart illustrating the first calculation operation example of the MFB50 in the internal combustion engine control device of the embodiment example.

[0043] Figure 14 This is a flowchart illustrating the second calculation operation example of the MFB50 in the internal combustion engine control device of the embodiment example.

[0044] Figure 15 This is an explanatory diagram showing the third calculated operation example of MFB50 in the internal combustion engine control device of the embodiment example.

[0045] Figure 16A and Figure 16B This indicates the existing relationship between in-cylinder pressure corresponding to crank angle and engine speed. Figure 16A It is a graph showing the relationship between crank angle and cylinder pressure. Figure 16B It is a graph showing the relationship between crank angle and engine speed.

[0046] Figure 17 This is a graph showing the existing relationship between θω_MAX and MFB50. Detailed Implementation

[0047] The following are implementation examples of the internal combustion engine control device and internal combustion engine control method, with reference to... Figures 1 to 15 Explanation is provided. Additionally, common components across all diagrams are marked with the same symbol.

[0048] 1. Implementation Examples

[0049] 1-1. Structural Example of Internal Combustion Engine Control

[0050] First, regarding the structural example of the internal combustion engine control device in the implementation example (hereinafter referred to as "this example"), refer to... Figures 1 to 3 Please provide an explanation.

[0051] Figure 1 This is a schematic structural diagram showing an example of an internal combustion engine in which the internal combustion engine control device is mounted.

[0052] Figure 1 The internal combustion engine 100 shown is a cylinder injection type engine. The internal combustion engine 100 is a four-stroke engine that repeatedly performs four strokes: intake stroke, compression stroke, combustion (expansion) stroke, and exhaust stroke. Furthermore, the internal combustion engine 100 can be, for example, a multi-cylinder engine with three cylinders. However, the number of cylinders in the internal combustion engine 100 is not limited to three; it can also have four or six or more cylinders.

[0053] The internal combustion engine 100 includes an air flow sensor 1 for measuring the intake air volume, a compressor 2 for pressurizing the intake air, an intercooler 3 for cooling the compressed intake air, and a throttle valve 4 for regulating the gas drawn into the cylinder block 5. Then, a throttle valve sensor 17 for detecting the opening degree of the throttle valve 4 is provided near the throttle valve 4.

[0054] Furthermore, the internal combustion engine 100 includes spark plugs 6 that supply ignition energy to the cylinder block 5 of each cylinder, fuel injection devices 9 that inject fuel into the cylinder block 5 of each cylinder, and pistons 10 that compress the fuel-air mixture flowing into the cylinder block 5. Moreover, the internal combustion engine 100 includes an intake valve 7 that adjusts the air-fuel mixture flowing into the cylinder block 5, and an exhaust valve 8 that discharges the exhaust gases after combustion.

[0055] Additionally, the internal combustion engine 100 includes a crank angle sensor 11 for detecting signals from a signal rotor 13 mounted on the crankshaft, and a water temperature sensor 12 for measuring the temperature of the cooling water. Furthermore, the internal combustion engine 100 includes a turbine 14 that transmits the kinetic energy of the exhaust gases to the compressor 2 via a shaft, and a three-way catalytic converter 15 that purifies harmful substances in the exhaust gases. Then, near the three-way catalytic converter 15, an A / F sensor 16 is installed to detect the oxygen concentration in the exhaust gases.

[0056] The aforementioned air flow sensor 1, crank angle sensor 11, water temperature sensor 12, A / F sensor 16, throttle valve sensor 17, and acceleration sensor 18 (for reference) detect the amount of acceleration. Figure 2 The output signals of various sensors, such as the engine control unit (ECU), are input to the engine control unit 200 that controls the internal combustion engine 100.

[0057] [ECU Structure]

[0058] Next, refer to Figure 2 The structure of the internal combustion engine control device 200 that controls the internal combustion engine 100 will be described.

[0059] Figure 2 This is a block diagram showing the structure of the internal combustion engine control device 200.

[0060] like Figure 2 As shown, the internal combustion engine control unit 200 includes an input circuit 201, an input / output port 202, a RAM (Random Access Memory) 203, a ROM (Read Only Memory) 204, and a CPU (Central Processing Unit) 205. Furthermore, the internal combustion engine control unit 200 includes a throttle valve drive circuit 206, a fuel injection device drive circuit 207, and an ignition output circuit 208. The throttle valve drive circuit 206, the fuel injection device drive circuit 207, and the ignition output circuit 208 are electrically controlled circuits.

[0061] The input circuit 201 receives outputs from various sensors, including the throttle valve sensor 17, air flow sensor 1, crank angle sensor 11, water temperature sensor 12, A / F sensor 16, and acceleration sensor 18. The input circuit 201 performs noise removal and other signal processing on the input signals before sending them to the input / output port 202. The values ​​input to the input port 202 are stored in RAM 203.

[0062] ROM 204 stores control programs describing the various arithmetic operations performed by CPU 205, as well as MAPs and data tables used in each operation. RAM 203 contains storage areas for values ​​input to the input ports of input / output port 202 and values ​​representing the operating quantities of each actuator calculated according to the control program. Furthermore, the values ​​representing the operating quantities of each actuator stored in RAM 203 are sent to the output ports of input / output port 202.

[0063] The drive signal for achieving the target opening degree of the throttle valve 4, set at the output port of input / output port 202, is sent to the motor driving the throttle valve 4 via the throttle valve drive circuit 206. The drive signal for the fuel injection device 9 is an ON / OFF signal, ON when the valve is open and OFF when the valve is closed. The drive signal for the fuel injection device 9, set at the output port of input / output port 202, is amplified by the fuel injection device drive circuit 207 to provide sufficient energy for driving the fuel injection device 9, and then supplied to the fuel injection device 9.

[0064] The operating signal output to spark plug 6 is an ON / OFF signal that is ON when current flows through the primary coil in the ignition output circuit 208 and OFF when no current flows. The ignition timing of spark plug 6 is the moment when the operating signal output by spark plug 6 changes from ON to OFF. The operating signal output to spark plug 6, set at the output port of input / output port 202, is amplified by the ignition output circuit 208 to provide sufficient energy for ignition and supplied to spark plug 6.

[0065] Additionally, a combustion detection unit 300 for calculating MFB50 is provided in CPU205 (see reference). Figure 3 ).

[0066] [Structure of the Combustion Detection Unit]

[0067] Next, refer to Figure 3 The structure of the combustion detection unit 300 will be explained.

[0068] Figure 3 This is a block diagram showing the structure of the combustion detection unit 300.

[0069] like Figure 3As shown, the combustion detection unit 300 includes a speed conversion unit 301, a θω_MAX detection unit 302, an MFB50 calculation unit 303, an average value calculation unit 304, and a deviation calculation unit 305.

[0070] The speed conversion unit 301 converts the measured crank angle into the speed of the internal combustion engine 100. For example, the speed conversion unit 301 converts the number of pulse signals from the crank angle sensor 11 input from the RAM 203 into a speed signal representing the speed value (hereinafter referred to as "speed"). Then, the speed conversion unit 301 outputs the converted speed to the θω_MAX detection unit 302. Here, the speed conversion unit 301 uses a first approximation curve (reference) that approximates the speed corresponding to the crank angle. Figure 16B Convert crank angle into speed.

[0071] The maximum speed detection unit, namely the θω_MAX detection unit 302, detects the maximum speed (hereinafter referred to as "θω_MAX") based on the input speed signal. Then, the θω_MAX detection unit 302 outputs the detected θω_MAX to the MFB50 calculation unit 303.

[0072] The combustion center of gravity calculation unit, i.e., the MFB50 calculation unit 303, has multiple calibration curves representing the relationship between MFB50 and θω_MAX for each of the multiple cylinders. Then, based on θω_MAX output from the θω_MAX detection unit 302 and the calibration curves, the MFB50 calculation unit 303 calculates the MFB50 for each cylinder. The MFB50 calculation unit 303 then outputs the calculated MFB50 (hereinafter referred to as "calculated MFB50") to the ignition output circuit 208. The ignition output circuit 208 adjusts the ignition timing of each cylinder in a manner that brings the calculated MFB50 closer to a pre-set target MFB50.

[0073] As described later, when adjusting the ignition timing of each cylinder individually, the phase change of θω_MAX of other cylinders (hereinafter referred to as "the target cylinders") connected to each other via the crankshaft is considered. Therefore, the MFB50 calculation unit 303 corrects the calibration curve of the target cylinders and calculates the MFB50 of the target cylinders based on the corrected calibration curve.

[0074] The average averaging unit 304 receives the adjusted ignition times #n and #n+1 of the cylinder for which ignition timing control is implemented from RAM 203. The average averaging unit 304 calculates the average value (hereinafter referred to as "average ignition time") t1 of the input ignition times. Then, the average averaging unit 304 outputs the average ignition time t1 to the deviation calculation unit 305.

[0075] The deviation calculation unit 305 receives the ignition time t0 of the target cylinder (hereinafter referred to as "target cylinder ignition time") from the RAM 203. Then, the deviation calculation unit 305 calculates the deviation between the average ignition time t1 and the target cylinder ignition time t0. The deviation calculation unit 305 outputs the calculated deviation to the MFB50 calculation unit 303.

[0076] The MFB50 calculation unit 303 uses the θω_MAX of the target cylinder output from the θω_MAX detection unit 302 to calculate the MFB50 before correction based on the calibration curve before correction. Furthermore, the MFB50 calculation unit 303 includes an addition unit 307 and a calibration curve correction unit 306. The addition unit 307 adds the deviation output from the deviation calculation unit 305 to the calculated MFB50 before correction. The value obtained by adding the values ​​using the addition unit 307 is the corrected MFB50. Then, the addition unit 307 outputs the corrected MFB50 to the calibration curve correction unit 306.

[0077] The calibration curve correction unit 306 corrects the calibration curve of the target cylinder based on the corrected MFB50. Then, the MFB50 calculation unit 303 uses the corrected calibration curve and θω_MAX output from the θω_MAX detection unit 302 to calculate the MFB50 of the target cylinder. Furthermore, the MFB50 calculation unit 303 outputs the calculated MFB50 of the target cylinder to the ignition output circuit 208. Then, the ignition output circuit controls the ignition timing of the target cylinder based on the calculated MFB50 output from the MFB50 calculation unit 303.

[0078] 1-2. Ignition Timing Control

[0079] Next, the ignition timing control in the internal combustion engine control device 200 with the above-described structure will be explained. In the example shown below, a three-cylinder engine will be used as an example.

[0080] [Mean Ignition Time Control]

[0081] First, refer to Figure 4 and Figure 5 The average ignition time control, which is the existing ignition time control, will be explained.

[0082] Figure 4 This is an explanatory diagram illustrating existing mean ignition time control. Figure 5 This is a diagram illustrating an example of existing average ignition time control. Figure 5 The graphs in the diagram show the cylinder pressure, ignition time, and combustion center of gravity (MFB50) at the top. Then, in... Figure 5 The lower part of each curve in the diagram illustrates the rotational speed and its maximum value, θω_MAX. Additionally, as... Figure 5As shown, the calibration curves for θω_MAX and MFB50 for each cylinder were generated under the condition that the ignition time of all cylinders is the same.

[0083] like Figure 4 As shown, in existing ignition timing control, the maximum angular velocity, θω_MAX, is first detected based on the signal from the crank angle sensor. Furthermore, θω_MAX is common to all cylinders. Then, using θω_MAX, according to... Figure 5 The calibration curves for each cylinder are shown to calculate the MFB50 for each cylinder. Furthermore, the average MFB50 of the calculated MFB50 for each cylinder is calculated. Then, the ignition time ta is calculated in a way that makes the average MFB50 an appropriate MFB50. The calculated ignition time ta is as follows: Figure 5 As shown, this is common to all cylinders. Then, the calculated ignition timing ta is output to the ignition output circuit, and the spark plugs of each cylinder ignite based on the calculated ignition timing ta.

[0084] Furthermore, by setting appropriate ignition timings for each cylinder, the combustion efficiency of an internal combustion engine can be improved. Therefore, cylinder ignition timing control is used, which specifies an inherent ignition timing for each cylinder.

[0085] [Ignition timing control for each cylinder]

[0086] Next, refer to Figures 6 to 10 This example explains the ignition timing control method, which involves controlling the ignition timing of each cylinder separately.

[0087] Figure 6 This is an explanatory diagram showing the ignition timing control of each cylinder. Figure 7 , Figure 8 and Figure 10 This is a diagram illustrating a control example for controlling the ignition timing of each cylinder. Figure 7 , Figure 8 and Figure 10 The graphs in the diagram show the cylinder pressure, ignition time, and combustion center of gravity (MFB50) at the top. Then, in... Figure 7 , Figure 8 and Figure 10 The lower part of each curve in the diagram shows the rotational speed and its maximum value, θω_MAX.

[0088] like Figure 6 As shown, in the ignition timing control of each cylinder, the maximum angular velocity, θω_MAX, is detected based on the signal from the crank angle sensor. Additionally, as... Figure 7As shown, for cylinders 1, 2, and 3, calibration curves representing the relationship between the combustion center of gravity (MFB50) and the maximum angular velocity (θω_MAX) were established. Then, based on the calibration curves of each cylinder, MFB50 was calculated for each cylinder.

[0089] In the ignition timing control of each cylinder, the ignition timing of each cylinder is calculated and adjusted to make the calculated MFB50 of each cylinder the optimal MFB50, i.e., the target MFB50. Furthermore, in the following description, adjusting the ignition timing of a cylinder is considered as implementing ignition timing control for each cylinder. Additionally, ignition timing control for each cylinder may be implemented individually for multiple cylinders, for example, when the vehicle in which the internal combustion engine 100 is mounted is in operation, or when the difference between the calculated MFB50 and the target MFB50 exceeds a preset threshold.

[0090] in addition, Figure 7 The example shown illustrates a case where ignition timing control is applied only to cylinders 1 and 2. These cylinders 1 and 2 are equivalent to the adjusted cylinders. Additionally, an example is shown where the adjustment range A1 for the ignition timings of cylinders 1 and 2 is the same. Therefore, the average value (hereinafter referred to as "average ignition time") t1 of the adjusted ignition timings of cylinders 1 and 2 is the same as the adjusted ignition timing.

[0091] like Figure 7 As shown, because the ignition timings of cylinders 1 and 2 change, the phase of MFB50 in cylinders 1 and 2 also changes. Therefore, the phase of θω_MAX also changes by an adjustment range B1. Thus, in cylinders 1 and 2, the phases of MFB50 and θω_MAX change together, so the calibration curves for cylinders 1 and 2 remain unchanged.

[0092] Figure 8 It is a graph showing the changes in the calibration curve caused by the control of the ignition timing of each cylinder.

[0093] Here, cylinders 1, 2, and 3 are interconnected via a crankshaft. For example... Figure 8 As shown, the phase change of MFB50 in cylinders 1 and 2 propagates to cylinder 3, and θω_MAX in cylinder 3 changes in the same way as in cylinders 1 and 2. However, the ignition timing of cylinder 3 is not adjusted, so the phase of MFB50 in cylinder 3 does not change.

[0094] As a result, in cylinder 3, only the phase of θω_MAX changes, so the actual correction curve representing the relationship between θω_MAX and MFB50 shifts from a dashed line to a solid line. Therefore, Figure 8The dashed line shown is an inappropriate correction curve for the phase change of θω_MAX of this cylinder (cylinder 3) caused by the phase change of MFB50 of other cylinders (cylinder 1 and cylinder 2) without considering the phase change of the ignition timing of each cylinder.

[0095] Figure 9 This is a graph showing the calculated MFB50 under the condition of using an inappropriate correction curve. Figure 9 The horizontal axis represents time.

[0096] like Figure 9 As shown, when MFB50 is calculated using an inappropriate correction curve that does not consider the phase change of θω_MAX, a significant deviation occurs between the calculated value (solid line) and the measured value (dashed line) in cylinder 3. Therefore, to calculate MFB50 with high accuracy, the correction curve needs to be corrected from a dashed line to a solid line.

[0097] Here, as Figure 10 As shown, the deviation between the ignition timing t0 of the target cylinder (cylinder 3) and the average ignition timing t1 of the adjusted ignition timings of cylinders 1 and 2 (where ignition timing control of each cylinder is implemented) is A2. Then, let C1 be the deviation between the phase of the MFB50 of the target cylinder before correction and the MFB50 of the cylinder that changes through ignition timing control of each cylinder. At this point, it can be seen that the ignition timing deviation A2 is equal to the MFB50 deviation C1. Therefore, in the internal combustion engine control device 200 of this example, the correction curve of the target cylinder is corrected using the relationship between the ignition timing deviation and the MFB deviation.

[0098] Next, refer to Figure 11 The correction process for the calibration curve is explained.

[0099] Figure 11 This is an explanatory diagram showing a summary of the correction process for the calibration curve.

[0100] like Figure 11 As shown, the maximum angular velocity, θω_MAX, is detected based on the signal from the crank angle sensor. Then, the MFB50 before correction is calculated based on the pre-correction calibration curve in the target cylinder and the detected θω_MAX. Next, the deviation (difference) A2 between the average ignition time t1 of the cylinders with adjusted ignition timing control and the ignition time t0 of the target cylinder is calculated. Then, the calibration curve is corrected by adding the calculated deviation A2 to the pre-correction MFB50.

[0101] Furthermore, the above example illustrates how to correct the calibration curve by adding deviation A2, but it is not limited to this. For example, the calibration curve can also be corrected by various other methods, such as calculating the correction value based on deviation A2 or multiplying the calculated correction value by MFB50.

[0102] Figure 12 This is a graph showing the calculated MFB50 based on the corrected calibration curve. Figure 12 The horizontal axis represents time. Figure 12 The solid lines in the diagram represent estimated values, while the dashed lines represent measured values.

[0103] like Figure 12 As shown, by correcting the calibration curve, the calculated value of the target cylinder, namely the third cylinder, i.e., the calculated MFB50, can be made close to the measured value, i.e., the true value MFB50. In this way, even with the ignition timing control of each cylinder implemented, MFB50 can be calculated with high accuracy.

[0104] 2. Example of calculating the combustion center of gravity (MFB50)

[0105] 2-1. Example of the first calculation action

[0106] Next, for the first calculated operation example of MFB50 implemented in the internal combustion engine control device 200 of this example, refer to... Figure 13 Please provide an explanation.

[0107] Figure 13 This is a flowchart representing the first calculation action example of MFB50. Figure 13 In the first example of calculation shown, the operation of controlling the ignition timing of each cylinder in the first and second cylinders of a three-cylinder engine and calculating the MFB50 of the third cylinder is explained.

[0108] First, the CPU205 calculates the ignition timing of cylinders 1 and 2 based on the calculated MFB50 of cylinders 1 and 2 calculated by the MFB50 calculation unit 303. That is, the ignition timing is calculated in a way that makes the calculated MFB50 close to the target MFB50. Then, based on the calculated ignition timing, the CPU205 performs ignition timing control of each cylinder to adjust the ignition timing of cylinders 1 and 2 (step S11).

[0109] Next, the averaging unit 304 obtains the adjusted ignition times of the first and second cylinders, for which ignition timing control has been implemented, from the RAM 203. Then, the averaging unit 304 calculates the average value of the adjusted ignition times of the first and second cylinders, i.e., the average ignition time t1 (step S12).

[0110] Next, the MFB50 calculation unit 303 calculates the MFB50 based on the maximum angular velocity θω_MAX of the third cylinder, which does not implement ignition timing control for each cylinder, and the correction curve before correction (step S13).

[0111] Additionally, the deviation calculation unit 305 calculates the deviation A2 between the average ignition time t1 and the ignition time t0 of the third cylinder (step S14). Then, the deviation calculation unit 305 inputs the calculated deviation A2 to the MFB50 estimation unit 303. The addition unit 307 of the MFB50 estimation unit 303 adds the deviation A2 calculated in step S14 to the MFB50 obtained in step S13, and calculates the corrected MFB50 (step S15).

[0112] Next, the calibration curve correction unit 306 corrects the calibration curve of the third cylinder based on the corrected MFB50 calculated in step S15 (step S16). Afterward, the MFB50 estimation unit 50 estimates the MFB50 of the third cylinder based on the corrected calibration curve from step S16. In this way, by taking into account the changes in θω_MAX caused by implementing ignition timing control for each cylinder, the estimation accuracy of the combustion center of gravity, i.e., MFB50, can be improved.

[0113] The first calculation example illustrates an instance of implementing individual ignition timing control for multiple cylinders, such as cylinder 1 and cylinder 2, and calculates the average value of the adjusted ignition timings for cylinder 1 and cylinder 2, but is not limited to this. For example, if individual ignition timing control is implemented only for cylinder 1, the deviation calculation unit 305 calculates the deviation between the adjusted ignition timing of cylinder 1 and the ignition timing of cylinder 2, for which individual ignition timing control is not implemented.

[0114] Then, the MFB50 calculation unit 303 uses this deviation to correct the calibration curve of the second cylinder. Next, the deviation calculation unit 305 calculates the deviation between the adjusted ignition time of the first cylinder and the ignition time of the third cylinder, for which ignition timing control for each cylinder is not implemented. Then, the MFB50 calculation unit 303 uses this deviation to correct the calibration curve of the third cylinder. Thus, the influence of cylinders with implemented ignition timing control on other cylinders can be considered, thereby improving the calculation accuracy of the MFB50.

[0115] Furthermore, this example illustrates how the MFB50 calculation unit 303 corrects for each cylinder by having a correction curve representing the relationship between the maximum angular velocity (θω_MAX) and the fuel center of gravity (MFB50), but it is not limited to this. For example, the MFB50 calculation unit 303 could also have a mathematical formula or mapping table for each cylinder, and correct such a formula or mapping table, as data representing the relationship between the maximum angular velocity (θω_MAX) and the fuel center of gravity (MFB50).

[0116] 2-2. Example of the second calculation action

[0117] Next, refer to Figure 14 The second calculation example for MFB50 will be explained.

[0118] Figure 14 This is a flowchart illustrating the second calculation action example of MFB50. Figure 14 The second calculation example shown illustrates the state after correcting the ignition timings of cylinders 1, 2, and 3 in a four-cylinder engine, and adjusting the calibration curve for cylinder 4. Additionally, Figure 14 In the illustrated action example, we assume that cylinder 3 stops due to cylinder stop control. Here, after correcting the calibration curve, there is a possibility of a change in the mean ignition time when cylinder stop is implemented. Therefore, Figure 14 In the example shown, when the cylinder stops, the average ignition time is calculated again based on the ignition time of the active cylinder, i.e., the cylinder that does not stop.

[0119] like Figure 14 As shown, CPU205 performs ignition timing control on each of cylinders 1, 2, and 3 (step S21). In step S21, the correction curve correction unit 306 of MFB50 calculation unit 303 corrects the correction curve of cylinder 4 based on the average ignition time of the adjusted ignition times of cylinders 1, 2, and 3 and the deviation from the ignition time of cylinder 4.

[0120] Next, the CPU205 performs cylinder stop detection based on various sensors and command signals set in the internal combustion engine 100 (step S22). Then, the CPU205 determines whether cylinder stop has been performed (step S23). In the process of step S23, if it is determined that cylinder stop has not been performed (step S23 is determined to be NO), the process ends. That is, the MFB50 of the fourth cylinder is calculated based on the correction curve corrected in the process of step S21.

[0121] In contrast, in the processing of step S23, if it is determined that the cylinder has been stopped (step S23 is determined to be YES), the average value calculation unit 304 calculates the average value of the adjusted ignition time of the cylinders that have not been stopped, namely the first cylinder and the second cylinder (average ignition time) (step S24).

[0122] Next, the MFB50 calculation unit 303 calculates the MFB50 based on the maximum angular velocity θω_MAX of the fourth cylinder, which does not implement ignition timing control for each cylinder, and the correction curve before correction (step S25).

[0123] Additionally, the deviation calculation unit 305 calculates the deviation between the average ignition time recalculated in step S24 and the ignition time of the fourth cylinder (step S26). Then, the deviation calculation unit 305 inputs the calculated deviation to the MFB50 estimation unit 303. The addition unit 307 of the MFB50 estimation unit 303 adds the deviation calculated in step S26 to the MFB50 obtained in step S25, and calculates the corrected MFB50 (step S27).

[0124] Next, the calibration curve correction unit 306 corrects the calibration curve of the fourth cylinder based on the corrected MFB50 calculated in step S27 (step S28). Afterward, the MFB50 calculation unit 50 calculates the MFB50 of the fourth cylinder based on the corrected calibration curve from step S28. Furthermore, when the stopped third cylinder becomes active, the average value calculation unit 304 again performs ignition timing control for each cylinder and calculates the average ignition timing of the active (combustion state) cylinders.

[0125] In this way, by detecting the stopping and combustion states of the cylinder, and calculating the average ignition time based solely on the ignition time of the active cylinder, the calibration curve of the target cylinder can be appropriately corrected, thereby improving the calculation accuracy of MFB50.

[0126] 2-3. Example of the third calculation action

[0127] Next, refer to Figure 15 The third calculation action of MFB50 will be explained.

[0128] Figure 15 This is an explanatory diagram illustrating the third calculation action example of MFB50. Figure 15 The third calculation example shown illustrates the situation where ignition timing control is implemented for all cylinders, including cylinders 1, 2, 3, and 4, in a four-cylinder engine.

[0129] like Figure 15As shown, by implementing ignition timing control for each cylinder, the ignition timing of cylinder 1 is adjusted from ignition timing tn1 to ignition timing tm1, and the ignition timing of cylinder 2 is adjusted from ignition timing tn2 to ignition timing tm2. Then, the ignition timing of cylinder 3 is adjusted from ignition timing tn3 to ignition timing tm3, and the ignition timing of cylinder 4 is adjusted from ignition timing tn4 to ignition timing tm4. Therefore, the phase of MFB50 for each cylinder also changes. Furthermore, because each cylinder is connected via a crankshaft, the phase of θω_MAX for each cylinder also changes accordingly.

[0130] Because the ignition timing of each cylinder is controlled individually, the adjustment range of the ignition timing differs for each cylinder, resulting in a deviation in the phase change of MFB50. Furthermore, the deviations Δ#1, Δ#2, Δ#3, Δ#4 between the adjusted ignition timings tm1, tm2, tm3, tm4 and the average ignition timing t_ave for each cylinder are approximately equal to the deviations Δ#1, Δ#2, Δ#3, Δ#4 between the MFB50 of each cylinder and the average MFB50_ave.

[0131] Therefore, the average ignition calculation unit 304 calculates the average ignition time t_ave based on the known adjusted ignition times tm1, tm2, tm3, and tm4 for each cylinder. Then, the deviation calculation unit 305 calculates the deviations #1, Δ#2, Δ#3, and Δ#4 between the ignition times tm1, tm2, tm3, and tm4 for each cylinder and the average ignition time t_ave. Additionally, the MFB50 estimation unit 50 estimates the MFB50 for each cylinder based on θω_MAX and the calibration curve before correction. As described above, since θω_MAX varies similarly for each cylinder, the MFB50 estimated based on the calibration curve before correction is approximately equal to the average value MFB50_ave.

[0132] Then, the MFB50 calculation unit 50 adds the deviations #1, Δ#2, Δ#3, and Δ#4 calculated by the deviation calculation unit 305 to the average value MFB50_ave, correcting the calibration curve for each cylinder. Afterward, the MFB50 calculation unit 50 calculates the MFB50 for each cylinder based on the corrected calibration curve. Thus, even when the ignition timing of each cylinder is controlled individually, the MFB50 for each cylinder can be calculated with high accuracy.

[0133] Furthermore, the present invention is not limited to the embodiments shown above and in the accompanying drawings, and various modifications can be made without departing from the spirit of the invention as described in the claims.

[0134] For example, the above embodiments have described the structure of the apparatus and system in detail for ease of understanding of the present invention, and are not limited to including all the structures described. Furthermore, a portion of the structure of the embodiments described herein can be replaced with the structure of other embodiments, and it is also possible to add structures of other embodiments to the structure of a certain embodiment. Additionally, for a portion of the structure of an embodiment, other structures can be added, deleted, or replaced.

[0135] In addition, the control lines and information lines shown are those deemed necessary for the description, but do not necessarily represent all control lines and information lines on the product. In fact, it can be assumed that almost all structures are interconnected.

[0136] Explanation of reference numerals in the attached figures

[0137] 1…Air Flow Sensor

[0138] 5… Cylinder block (cylinder)

[0139] 6…spark plugs

[0140] 10… Piston

[0141] 11…Crank Angle Sensor

[0142] 13…Signal Rotor

[0143] 100…internal combustion engine

[0144] 200… Internal Combustion Engine Control Unit (ECU)

[0145] 201…Input Circuit

[0146] 202… Input / output ports

[0147] 203…RAM

[0148] 204…ROM

[0149] 205…CPU

[0150] 206…Throttle valve drive circuit

[0151] 207… Fuel Injection Device Drive Circuit

[0152] 208… Ignition Output Circuit

[0153] 300… Combustion Detection Department

[0154] 301…Speed ​​Converter

[0155] 302…θω_MAX Detection Unit (Maximum Rotation Speed ​​Detection Unit)

[0156] 303…MFB50 Estimation Department (Combustion Center of Gravity Estimation Department)

[0157] 304…Average Calculation Section

[0158] 305… Deviation Calculation Department

[0159] 306…Correction Curve Correction Section

[0160] 307…Addition Department.

Claims

1. An internal combustion engine control device for individually adjusting and controlling the ignition timing of multiple cylinders, characterized in that, include: The speed conversion unit converts the crank angle of the crankshaft connected to the cylinder into the speed of the internal combustion engine; The maximum speed detection unit detects the maximum value of the speed after conversion by the speed conversion unit; The combustion center of gravity calculation unit calculates the combustion center of gravity of the cylinder based on the maximum value of the rotational speed; and The deviation calculation unit calculates the deviation between the adjusted ignition time of the cylinder after ignition timing adjustment and the ignition time of the target cylinder (which may be the same as or different from the adjusted cylinder) among the plurality of cylinders. The combustion center of gravity estimation unit changes the relationship between the maximum value of the rotational speed used when estimating the combustion center of gravity of the target cylinder and the combustion center of gravity based on the deviation calculated by the deviation calculation unit.

2. The internal combustion engine control device as described in claim 1, characterized in that: The combustion center of gravity calculation unit has a correction curve for each of the plurality of cylinders, representing the relationship between the maximum value of the rotational speed and the combustion center of gravity. It also has a correction curve correction unit, which corrects the correction curve of the target cylinder based on the deviation calculated by the deviation calculation unit.

3. The internal combustion engine control device as described in claim 2, characterized in that: The combustion center of gravity calculation unit Based on the maximum value of the change in the rotational speed when the ignition timing of the adjusted cylinder was adjusted, the original combustion center of gravity of the cylinder to be corrected was calculated. The correction curve correction unit corrects the correction curve by adding the deviation to the calculated combustion center of gravity before correction.

4. The internal combustion engine control device as described in claim 1, characterized in that: It includes an average value calculation unit, which, when multiple adjusted cylinders exist, calculates the average value of the adjusted ignition times of the multiple adjusted cylinders. The deviation calculation unit calculates the deviation between the average value and the ignition timing of the target cylinder.

5. The internal combustion engine control device as described in claim 4, characterized in that: When the average value calculation unit detects that one of the adjusted cylinders has stopped, it again calculates the average value of the adjusted ignition time of the cylinders that have not stopped among the adjusted cylinders. The deviation calculation unit calculates the deviation between the average value obtained from the recalculation and the ignition time of the cylinder to be corrected.

6. The internal combustion engine control device as described in claim 4, characterized in that: The cylinder to be corrected is the same cylinder as the cylinder after adjustment. The deviation calculation unit calculates the deviation between the average value and the adjusted ignition time of the target cylinder.

7. The internal combustion engine control device as described in claim 1, characterized in that: The cylinder to be corrected is a different cylinder from the cylinder after adjustment.

8. A method for controlling the ignition timing of multiple cylinders individually, characterized in that, include: The process of converting the crank angle of the crankshaft connected to the cylinder into the speed of the internal combustion engine; The process of detecting the maximum value of the converted rotational speed; The process of calculating the deviation between the adjusted ignition time of the cylinder after adjusting the ignition time in the plurality of cylinders and the ignition time of the correction target cylinder that is the same as or different from the adjusted cylinder in the plurality of cylinders. and Based on the aforementioned deviation, the relationship between the maximum value of the rotational speed used in calculating the combustion center of gravity of the target cylinder and the combustion center of gravity is changed, and the process of calculating the combustion center of gravity of the target cylinder is performed.

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