Control device for internal combustion engine

Abstract

A control device for an internal combustion engine is provided with: a spark-ignition internal combustion engine; a sensor that detects the rotational speed and load of the internal combustion engine; and an ignition timing control unit that controls the ignition timing of the internal combustion engine on the basis of the rotational speed, the load, and the characteristics of a reference ignition timing determined to be the later one of an optimal ignition timing and a knock ignition timing that are predetermined on the basis of the rotational speed and the load. The optimal ignition timing is predetermined in accordance with the rotational speed and the load such that the torque is maximum. The knock ignition timing is predetermined so that knock does not occur when fuel of a reference octane number is supplied to the internal combustion engine. The ignition timing control unit calculates a first hysteresis amount obtained by multiplying the difference between the octane number of the fuel supplied to the internal combustion engine and the reference octane number by a predetermined hysteresis amount, corrects the knock ignition timing to be delayed by the first hysteresis amount, and controls the knock ignition timing according to the rotational speed and the load. When the operation region of the internal combustion engine is either a load region on the high load side from the optimal operation line or a maximum output region, a second hysteresis amount is calculated on the basis of the predetermined hysteresis amount, and the reference ignition timing is corrected to be delayed by the second hysteresis amount.

Description

Technical Field

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

[0002] In recent years, research and development efforts to improve fuel efficiency, which contributes to energy efficiency, have been underway to ensure that more people have access to cost-effective, reliable, sustainable, and advanced energy. A device that suppresses deterioration in the fuel efficiency performance of an internal combustion engine while reducing crank noise is known. For example, the device described in Patent Document 1 uses a knock sensor and a bandpass filter to detect crank noise within a specified frequency band. The detected crank noise is then compared with multiple thresholds, and multiple ignition maps used for ignition timing control are switched based on the comparison results.

[0003] However, if the characteristics of the ignition timing are stored in advance as a plurality of maps and switched according to the occurrence of the cranking sound as in the device of Patent Document 1, the computational load of the device required for controlling the ignition timing may become excessive.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2016-173081 (JP 2016-173081A). Summary of the Invention

[0007] A control device for an internal combustion engine according to one embodiment of the present invention includes: a spark-ignition internal combustion engine; a sensor for detecting the engine's rotational speed and load; and an ignition timing control unit for controlling the engine's ignition timing based on the rotational speed and load detected by the sensor and characteristics of a reference ignition timing, the reference ignition timing being determined as the later of an optimal ignition timing and a knock ignition timing predetermined based on the rotational speed and load. The optimal ignition timing is predetermined based on the rotational speed and load to maximize torque. The knock ignition timing is predetermined so that knock does not occur when fuel having a reference octane rating is supplied to the engine. The ignition timing control unit calculates a first lag amount obtained by multiplying the difference between the octane number of the fuel supplied to the internal combustion engine and the base octane number by a prescribed lag amount, and corrects the knock ignition timing to be delayed by the first lag amount. Furthermore, when, based on the speed and load detected by the sensor, the operating range of the internal combustion engine determined by the speed and load becomes either a predetermined load range on the high-load side of the optimal operating line in which the net fuel consumption rate of the internal combustion engine is the highest, or a maximum output range in which the output of the internal combustion engine is the highest, a second lag amount is calculated based on the prescribed lag amount, and the base ignition timing is corrected to be delayed by the second lag amount. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The objects, features and advantages of the present invention will be further clarified through the following description of the embodiments in conjunction with the accompanying drawings.

[0009] Figure 1 This is a block diagram schematically showing an example of the overall configuration of a control device for an internal combustion engine according to an embodiment of the present invention;

[0010] Figure 2 Is used to illustrate Figure 1 Figure 1 shows the virtual speed control of the motor generator by the ECU.

[0011] Figure 3 This is used to explain the virtual speed control. Figure 1 A diagram of the operating area of ​​the engine;

[0012] Figure 4 Is used to illustrate Figure 1 A diagram of the in-cylinder pressure when the engine is running at high load;

[0013] Figure 5 Is used to illustrate and Figure 4 a plot of the corresponding cylinder pressure levels;

[0014] Figure 6 It is schematically shown Figure 1 A block diagram of an example of the main structure of the device;

[0015] Figure 7 Is used to illustrate the Figure 6 a diagram of ignition timing set by an ignition timing control unit;

[0016] Figure 8 Is used to illustrate Figure 6 a diagram showing the setting of the ignition timing by the ignition timing control unit;

[0017] Figure 9 Is used to illustrate Figure 8 A plot of the characteristics of the coefficients of ;

[0018] Figure 10 It is shown by Figure 6 A flowchart of an example of a process performed by an ECU. DETAILED DESCRIPTION

[0019] Below, refer to Figures 1 to 10The embodiment of the present invention is described. The control device for an internal combustion engine according to the embodiment of the present invention can be applied to a vehicle equipped with a spark ignition type internal combustion engine. The following specifically describes an example of application to a series hybrid electric vehicle (Hybrid Electric Vehicle), which uses a spark ignition type internal combustion engine to drive a generator, and uses the generated electricity to drive an electric motor for driving. It should be noted that the present invention can also be similarly applied to a vehicle that can switch between a driving mode driven by a generator and a driving mode driven by an internal combustion engine, and a gasoline vehicle that does not have a generator.

[0020] Figure 1 1 is a block diagram schematically showing an example of the overall structure of an internal combustion engine control device (hereinafter referred to as a device) 100 according to an embodiment of the present invention. Figure 1 As shown, the device 100 mainly includes an engine 1 as a spark ignition internal combustion engine mounted on a vehicle (not shown), a motor generator 2 connected to the output shaft of the engine 1, and an electronic control unit (ECU) 10 for controlling the engine 1 and the motor generator 2. The output shaft of the motor generator 2 is connected to a drive shaft 3 of the vehicle.

[0021] Engine 1 is provided with an intake air sensor 1a for detecting the intake air volume of engine 1, a rotational speed sensor 1b for detecting the rotational speed of engine 1 (engine speed Ne), and a knock sensor 1c for detecting knock by detecting vibration of the cylinder block of engine 1. Drive shaft 3 is provided with a vehicle speed sensor 3a for detecting vehicle speed V based on the rotational speed of drive shaft 3. The intake air sensor 1a, rotational speed sensor 1b, knock sensor 1c, and vehicle speed sensor 3a are connected to ECU 10, and signals indicating the detection results of the intake air sensor 1a, rotational speed sensor 1b, knock sensor 1c, and vehicle speed sensor 3a are input to ECU 10.

[0022] Figure 2 This diagram illustrates the virtual speed change control performed by the ECU 10 on the motor generator 2. Operating the engine 1 to increase power generation efficiency (net fuel consumption) regardless of vehicle speed V can improve fuel efficiency, but this can also cause discomfort to the driver. By simulating a state where the engine 1 and drive shaft 3 are connected via a step-variable transmission and controlling the engine speed Ne to increase or decrease according to vehicle speed V (virtual speed change control), this discomfort can be prevented.

[0023] The ECU 10 controls the engine speed Ne by the speed of the motor generator 2. More specifically, Figure 2As shown, the engine speed Ne is increased or decreased according to the vehicle speed V between a predetermined upper speed limit NeH and a lower speed limit NeL. For example, when the vehicle speed V is 0 or higher and lower than a threshold value V1, the engine speed Ne is increased or decreased at a rate of change R1; when the vehicle speed V is 0 or higher and lower than a threshold value V2, the engine speed Ne is increased or decreased at a rate of change R2; when the vehicle speed V is 0 or higher and lower than a threshold value V3, the engine speed Ne is increased or decreased at a rate of change R3; when the vehicle speed V is 3 or higher and lower than a threshold value V4, the engine speed Ne is increased or decreased at a rate of change R4; and when the vehicle speed V is 4 or higher, the engine speed Ne is increased or decreased according to the vehicle speed V (0 < V1 < V2 < V3 < V4, 0 < R1 < R2 < R3 < R4 < R5).

[0024] Figure 3 This diagram illustrates the operating range of engine 1 during virtual speed control. The operating range of engine 1 is determined by the engine speed (engine speed Ne) and load. The load of engine 1 can be expressed, for example, as engine 1 torque Tq and charging efficiency ηc. Charging efficiency ηc is the ratio (percentage) of the intake air volume (volume under standard conditions) per cycle to the cylinder capacity (displacement) of engine 1 and can be calculated based on the intake air volume from intake air volume sensor 1a. Torque Tq is proportional to charging efficiency ηc.

[0025] like Figure 3 As shown in FIG. 1 , when the virtual speed change control is not performed, the operating area along the optimal operating line with the highest net fuel consumption rate is used. On the other hand, when the virtual speed change control is performed, the engine speed Ne ( Figure 2 ), the torque Tq is determined by the engine speed Ne and the power generation of the motor generator 2, so a larger operating range including a high load range near the fully open action line is used.

[0026] Figure 4 1 is a diagram for explaining the in-cylinder pressure during high-load operation of the engine 1. Figure 5 Is used to illustrate and Figure 4 The corresponding cylinder pressure level diagram. In the high load area, Figure 4 The fluctuation of the in-cylinder pressure (combustion pressure) of the engine 1 shown becomes larger, thereby Figure 5 The cylinder pressure level shown increases, exciting the vibration of the crankshaft of the engine 1, etc. Figure 3 Within the operating range (abnormal noise generation region AR) of a predetermined engine speed Ne (Ne1 ≤ Ne ≤ Ne2, e.g., approximately 1800 rpm to 4200 rpm), vibrations at frequencies (e.g., approximately 200 Hz to 770 Hz) that may be perceived as abnormal noise by vehicle occupants may sometimes increase. The abnormal noise generation region AR is a high-load region near the full-throttle operating line, or at least an operating region higher in load than the optimal operating line. Hereinafter, the abnormal noise generation region AR may be referred to as the "load region."

[0027] In such an abnormal noise generating region AR, by retarding the ignition timing θ of the engine 1 and slowing the combustion rate, the fluctuations in the cylinder pressure can be moderated, the cylinder pressure level can be reduced, and the abnormal noise can be suppressed without limiting the torque Tq. For example, by determining different ignition timing θ characteristics (characteristic maps of ignition timing θ corresponding to engine speed Ne and load) for the abnormal noise generating region AR and other operating regions, and switching these characteristics according to the current operating region, it is possible to retard the ignition timing θ in the abnormal noise generating region AR.

[0028] However, according to the virtual speed change control speed number (in Figure 2 In this example, the ignition timing θ characteristic map is set to five levels (5 in the example) and change rates R1 to R5. The abnormal noise generation region AR may be frequently used, requiring frequent switching of the ignition timing θ characteristic map. In this case, the computational load required to control the ignition timing θ may become excessive. Therefore, in this embodiment, the device 100 is configured as follows to reduce the computational load required to control the ignition timing θ for suppressing abnormal noise by correcting the ignition timing θ according to the operating region of the engine 1.

[0029] Figure 6 1 is a block diagram schematically showing an example of the main structure of the device 100. Figure 1 and Figure 6 As shown, the device 100 primarily includes an ECU 10, to which an intake air amount sensor 1a, a rotation speed sensor 1b, a knock sensor 1c, a vehicle speed sensor 3a, an engine 1, and a motor generator 2 are connected. The ECU 10 comprises a computer including a processor such as a CPU, memory such as RAM (random access memory) and ROM (read-only memory), and other peripheral circuits. The ECU 10 includes a rotation speed control unit 11, an octane number estimation unit 12, and an ignition timing control unit 13 as functional components, and functions as the rotation speed control unit 11, the octane number estimation unit 12, and the ignition timing control unit 13.

[0030] The rotation speed control unit 11 is based on the vehicle speed V detected by the vehicle speed sensor 3a and a predetermined characteristic ( Figure 2 ), the engine speed Ne is controlled by the speed of the electric generator 2.

[0031] The octane number estimation unit 12 estimates the octane number of the fuel supplied to the engine 1. For example, when changes in both engine speed Ne and load are small, the ignition timing θ is gradually advanced, and the octane number corresponding to the ignition timing at which knocking is detected by the knock sensor 1c is estimated as the octane number of the fuel supplied to the engine 1. The octane number estimated by the octane number estimation unit 12 (estimated octane number) is stored in the memory of the ECU 10. Alternatively, the octane number (estimated octane number) of a designated fuel specified for each vehicle (e.g., regular gasoline, ethanol-gasoline blends (E100, E85), etc.) may be used as the octane number (estimated octane number) of the fuel supplied to the engine 1. In this case, for example, the average octane number of commercially available designated fuels (e.g., RON91 for regular gasoline) is pre-stored in the memory of the ECU 10 as the designated octane number. Then, the octane number estimation unit 12 reads the designated octane number stored in the memory of the ECU 10 and estimates it as the octane number of the fuel supplied to the engine 1 (estimated octane number).

[0032] Figure 7 This is a diagram for explaining the ignition timing θ of the engine 1 set by the ignition timing control unit 13, and shows an example of the characteristics of the ignition timing θ with respect to the charging efficiency ηc at a specific engine speed Ne (Ne1≤Ne≤Ne2). Figure 8 This is a diagram for explaining setting of the ignition timing θ by the ignition timing control unit 13 .

[0033] The characteristics of the optimal ignition timing θm at which the torque Tq of the engine 1 is maximized are predetermined based on the engine speed Ne and the charging efficiency ηc through combustion tests and stored as a characteristic map in the memory of the ECU 10. Furthermore, the characteristics of the knock ignition timing θk, the most advanced ignition timing at which knock does not occur, are also predetermined based on the engine speed Ne and the charging efficiency ηc through combustion tests and stored as a characteristic map in the memory of the ECU 10. Figure 7 and Figure 8 As shown, the ignition timing on the more retarded side of the optimum ignition timing θm and the knock ignition timing θk is set to the base ignition timing θ0 at which the torque Tq is maximized within a range where knocking does not occur.

[0034] The characteristics of the optimal ignition timing θm and the knock ignition timing θk are determined by supplying a fuel of a reference octane number to the engine 1 and conducting a combustion test. The reference octane number is the octane number of a reference fuel (e.g., high-octane gasoline). For example, the average octane number of commercially available reference fuels (e.g., high-octane gasoline RON95) is stored as the reference octane number in the memory of the ECU 10. The optimal ignition timing θm is a constant ignition timing independent of the octane number. On the other hand, since knock is more likely to occur as the octane number of the fuel decreases, the knock ignition timing θk shifts toward the retard side as the octane number decreases.

[0035] The ignition timing control unit 13 subtracts the base octane number from the estimated octane number to calculate the difference ΔRON between the estimated octane number and the base octane number. Then, when the estimated octane number is lower than the base octane number (ΔRON < 0), a first retardation amount Δθ1 is calculated by multiplying a predetermined retardation amount Δθ by the difference ΔRON (Δθ1 = ΔRON × Δθ), and the knock ignition timing θk is corrected to retard the first retardation amount Δθ1. In this way, when the octane number of the fuel supplied to the engine 1 (estimated octane number) is lower than the base octane number, making knock more likely to occur, the retardation correction of the knock ignition timing θk allows the ignition timing to be adjusted to a range where knock does not occur. The predetermined retardation amount Δθ is the retardation amount when the difference ΔRON between the estimated octane number and the base octane number is "1." It is determined in advance through combustion testing and stored in the memory of the ECU 10.

[0036] The ignition timing control unit 13 calculates the charging efficiency ηc based on the intake air amount detected by the intake air amount sensor 1a. It then refers to the characteristics of the optimal ignition timing θm and the knock ignition timing θk to determine a base ignition timing θ0 corresponding to the engine speed Ne and the charging efficiency ηc(load). Specifically, the optimal ignition timing θm is set as the base ignition timing θ0 in the low-load range, while the knock ignition timing θk is set as the base ignition timing θ0 in the high-load range.

[0037] When the engine speed Ne is within a predetermined abnormal noise generation region AR, where the engine speed Ne is greater than or equal to a first speed Ne1 and less than or equal to a second speed Ne2, and the charging efficiency ηc is greater than or equal to a predetermined value α, the ignition timing control unit 13 retardes the base ignition timing θ0. More specifically, the ignition timing control unit 13 calculates a second retardation amount Δθ2 (Δθ2 = k × Δθ), obtained by multiplying a predetermined retardation amount Δθ by a predetermined coefficient k, and retardes the base ignition timing θ0 by the second retardation amount Δθ2. In this manner, retarding the base ignition timing θ0 in the abnormal noise generation region AR slows the combustion speed, moderates fluctuations in the in-cylinder pressure, reduces the cylinder pressure level, and suppresses abnormal noise.

[0038] The ignition timing control unit 13 may also retard the reference ignition timing θ0 in the maximum output range of high speed and high load (near the maximum speed and near the full engine speed) where the output of the engine 1 is the maximum, similarly to the abnormal noise generation range AR. In the maximum output range, due to the fluctuation of the in-cylinder pressure of the engine 1 ( Figure 4 ), cylinder pressure level ( Figure 5 ) is greater than in the abnormal noise generation region AR, causing the combustion sound itself to become louder, potentially causing vehicle occupants to perceive the combustion sound as abnormal noise. In this maximum output region, similarly to the abnormal noise generation region AR, a second lag amount Δθ2 (Δθ2 = k × Δθ) is calculated by multiplying a predetermined lag amount Δθ by a predetermined coefficient k, and the base ignition timing θ0 is corrected to lag by the second lag amount Δθ2. By retarding the base ignition timing θ0 in the maximum output region as well, the combustion speed is slowed, the fluctuations in the in-cylinder pressure are mitigated, the cylinder pressure level is lowered, and abnormal noise is suppressed.

[0039] In this way, by performing retardation control of ignition timing θ through correction rather than switching characteristic maps, the computational load is reduced, allowing reliable and timely retardation control even when the abnormal noise generation region AR is frequently used through virtual speed change control. Furthermore, by calculating the second retardation amount Δθ2 of the reference ignition timing θ0 for suppressing abnormal noise using a common predetermined retardation amount Δθ, which is used in conjunction with the first retardation amount Δθ1 of the knock ignition timing θk corresponding to the fuel octane number, the computational load required for controlling ignition timing θ can be further reduced. In other words, by performing both retardation correction for adjusting the ignition timing to a range where knocking does not occur and retardation correction for suppressing abnormal noise using the same predetermined retardation amount Δθ, the computational load required for controlling ignition timing θ can be further reduced.

[0040] Figure 9 This is a diagram for explaining the characteristics of the coefficient k. The characteristics of the coefficient k are predetermined based on the engine speed Ne and the charging efficiency ηc through combustion tests and are stored in the memory of the ECU 10 as a characteristic map. Figure 9 As shown, the coefficient k is determined to be a value greater than "0" (e.g., a natural number) within the abnormal noise generation region AR (Ne1 ≤ Ne ≤ Ne2 and α ≤ ηc ≤ 100), and is determined to be "0" outside the abnormal noise generation region AR (Ne < Ne1 or Ne > Ne2 or ηc < α). The coefficient k can be determined to be a constant value within the abnormal noise generation region AR, or it can be determined to be a value that varies depending on the engine speed Ne or the charging efficiency ηc. In addition to the engine speed Ne and the charging efficiency ηc, the coefficient k can also be determined based on the octane number of the fuel supplied to the engine 1.

[0041] Although not shown in the figure, when retard correction of the base ignition timing θ0 is performed to suppress abnormal noise even in the maximum output range, the coefficient k is determined to be greater than 0 in the maximum output range in addition to the abnormal noise generation range AR. The coefficient k in the maximum output range can be determined to be the same value as that in the abnormal noise generation range AR, or a different value. In addition to the engine speed Ne and the charging efficiency ηc, the coefficient k in the maximum output range can also be determined based on the octane number of the fuel supplied to the engine 1.

[0042] The charging efficiency ηc of engine 1 is correlated with the in-cylinder pressure of engine 1 and, in turn, with the cylinder pressure level that excites vibrations that cause abnormal noise. By determining the coefficient k based on the charging efficiency ηc, the appropriate second hysteresis amount Δθ2 for suppressing abnormal noise can be calculated with high accuracy.

[0043] Figure 10 1 is a flowchart showing an example of processing executed by the ECU 10. The processing shown in this flowchart is started when the vehicle is started and the ECU 10 is started, and is repeatedly performed in units of predetermined time.

[0044] like Figure 10 As shown, first, in S1 (S: processing step), the difference ΔRON between the estimated octane number and the base octane number is calculated, and a determination is made as to whether the difference ΔRON is less than 0. If S1 is affirmative (S1: Yes), the estimated octane number is determined to be lower than the base octane number, and the process proceeds to S2. If S1 is negative (S1: No), the estimated octane number is determined to be not lower than the base octane number, and the process proceeds to S3. In S2, a predetermined retardation amount Δθ is multiplied by the difference ΔRON to calculate a first retardation amount Δθ1, and the knock ignition timing θk is corrected to retard the first retardation amount Δθ1.

[0045] In S3, a determination is made as to whether the current operating range corresponding to the engine speed Ne and the charging efficiency ηc(load) is within the abnormal noise generation range AR or the maximum output range. If S3 is affirmative (S3: Yes), the process proceeds to S4. If S3 is negative (S3: No), the process ends. In S4, a predetermined lag amount Δθ is multiplied by a coefficient k corresponding to the current engine speed Ne and the charging efficiency ηc(load) to calculate a second lag amount Δθ2. The base ignition timing θ0 is then corrected to lag by the second lag amount Δθ2.

[0046] According to the embodiments of the present invention, the following effects can be achieved.

[0047] (1) The device 100 includes: an engine 1 which is a spark ignition type internal combustion engine; sensors (intake air amount sensor 1a, rotation speed sensor 1b) which detect the rotation speed (engine speed Ne) and load (torque Tq, charging efficiency ηc) of the engine 1; and an ignition timing control unit 13 which controls the ignition timing θ of the engine 1 based on the rotation speed and load detected by the sensors and the characteristics of the reference ignition timing θ0, the reference ignition timing θ0 being determined as the later of the optimal ignition timing θm and the knock ignition timing θk which are predetermined based on the rotation speed and load ( Figure 1 、 Figure 6 、 Figure 7 The optimum ignition timing θm is predetermined based on the engine speed and load so that the torque Tq is maximized. The knock ignition timing θk is predetermined so that knocking does not occur when fuel of a reference octane number is supplied to the engine 1 .

[0048] The ignition timing control unit 13 calculates a first retardation amount Δθ1 obtained by multiplying the difference ΔRON between the octane number (estimated octane number) of the fuel supplied to the engine 1 and the reference octane number by a predetermined retardation amount Δθ, and corrects the knock ignition timing θk to be retarded by the first retardation amount Δθ1 ( Figure 7 、 Figure 10 Furthermore, when the operating range of the engine 1 defined by the speed and load detected by the sensor becomes either a predetermined load range (abnormal noise generation range AR) on the high-load side of the optimal operating line where the net fuel consumption rate of the engine 1 is the highest, or a maximum output range where the output of the engine 1 is the highest, a second lag amount Δθ2 is calculated based on the predetermined lag amount Δθ, and the reference ignition timing θ0 is corrected to lag the second lag amount Δθ2 ( Figures 7 to 9 、 Figure 10 S3~S4).

[0049] This allows the base ignition timing θ0 to be retarded in the abnormal noise generation region AR and the maximum output region without switching characteristic maps, thereby reducing the computational load on the device 100 required to control the ignition timing θ. Furthermore, by performing hysteresis correction using a common, predetermined retardation amount Δθ in both the adjustment of the knock ignition timing θk corresponding to the fuel's octane number (overall range) and the adjustment of the base ignition timing θ0 for suppressing abnormal noise (in the abnormal noise generation region AR and the maximum output region), the computational load required to control the ignition timing θ can be further reduced. Specifically, the control for retarding the knock ignition timing θk when fuel with a lower octane number than the base fuel corresponding to the predetermined knock ignition timing θk is supplied is also applied to the hysteresis correction of the base ignition timing θ0 for suppressing abnormal noise. This eliminates the need for separate control for suppressing abnormal noise and further reduces the computational load required to control the ignition timing θ by simplifying the overall control of the ignition timing θ.

[0050] (2) The ignition timing control unit 13 multiplies the predetermined retardation amount Δθ by a predetermined coefficient k to calculate a second retardation amount Δθ2 ( Figure 8 ).

[0051] (3) The device 100 further includes: a motor generator 2 connected to the engine 1; and a rotation speed control unit 11 that controls the rotation speed of the engine 1 by the rotation speed of the motor generator 2 ( Figure 6 When controlling the engine 1 speed via the speed of the motor generator 2, torque Tq is determined based on the engine speed Ne and the power generated by the motor generator 2. This allows for a wide operating range, including high-load areas. In high-load areas, fluctuations in in-cylinder pressure increase, raising the cylinder pressure level and potentially stimulating vibrations in the crankshaft of the engine 1, generating abnormal noise. By predetermining the abnormal noise generation region AR where such abnormal noise is likely to occur and retarding the base ignition timing θ0 within the abnormal noise generation region AR, both the computational load and the abnormal noise can be suppressed.

[0052] (4) The speed control unit 11 increases or decreases the engine speed Ne at different rates of change R1 to R5 according to the running speed (vehicle speed V) of the vehicle driven by the motor generator 2. Figure 2When performing such virtual speed control, the abnormal noise generation region AR is frequently used depending on the number of gear stages and the change rates R1 to R5. Therefore, when performing retardation control of the ignition timing θ by switching characteristic maps, the computational load is excessive, potentially making it difficult to perform appropriate retardation control. By performing retardation control of the ignition timing θ through correction rather than switching characteristic maps, the computational load is reduced, and even when the abnormal noise generation region AR is frequently used through virtual speed control, appropriate retardation control can be reliably performed.

[0053] The above embodiment can be modified in various ways. The following describes a modification. In the above embodiment, an example is described in which the filling efficiency ηc is calculated based on the intake air volume detected by the intake air volume sensor 1a and used as a physical quantity representing the load of the engine 1. However, the sensor for detecting the load of the spark ignition type internal combustion engine is not limited to this. For example, a sensor for detecting the torque Tq can also be used as the load of the engine 1. In the above embodiment, Figure 9 In the examples above, the predetermined value α is exemplified as a constant that does not depend on the engine speed Ne. However, the predetermined value α may be determined so as to vary according to the engine speed Ne.

[0054] The above-described embodiment and modified examples may be arbitrarily combined with one or more of them, and the modified examples may be combined with each other.

[0055] According to the present invention, the calculation load of the device required for controlling the ignition timing can be suppressed.

[0056] The present invention has been described above with reference to preferred embodiments. However, it should be understood by those skilled in the art that various modifications and changes can be made without departing from the scope of the claims.

Claims

1. A control device (100) for an internal combustion engine, characterized in that: have: Spark ignition internal combustion engine (1); Sensors (1a, 1b) for detecting the rotational speed and load of the internal combustion engine (1); An ignition timing control unit (13) controls the ignition timing of the internal combustion engine (1) based on the speed and load detected by the sensors (1a, 1b) and the characteristics of a reference ignition timing, wherein the reference ignition timing is determined to be the later of an optimal ignition timing and a knock ignition timing predetermined based on the speed and load. The optimal ignition timing is predetermined based on the rotational speed and the load so as to maximize the torque. The knock ignition timing is predetermined so that knock does not occur when fuel of a reference octane number is supplied to the internal combustion engine (1). The ignition timing control unit (13) calculates a first retardation amount obtained by multiplying a difference between the octane number of the fuel supplied to the internal combustion engine (1) and the reference octane number by a predetermined retardation amount, corrects the knock ignition timing to retard the first retardation amount, and The ignition timing control unit (13) calculates a second lag amount based on the specified lag amount and corrects the base ignition timing to lag by the second lag amount when the operating range of the internal combustion engine (1) specified by the speed and the load becomes either a predetermined load range on the high-load side of the optimal operation line where the net fuel consumption rate of the internal combustion engine (1) is the highest, or a maximum output range where the output of the internal combustion engine (1) is the highest, based on the speed and the load detected by the sensors (1a, 1b).

2. The control device (100) for an internal combustion engine according to claim 1, characterized in that The ignition timing control unit (13) calculates the second retardation amount by multiplying the predetermined retardation amount by a predetermined coefficient.

3. The control device (100) for an internal combustion engine according to claim 1 or 2, characterized in that: Also features: a motor generator (2) connected to the internal combustion engine (1); and A rotation speed control unit (11) controls the rotation speed of the internal combustion engine (1) by the rotation speed of the motor generator (2).

4. The control device (100) for an internal combustion engine according to claim 3, characterized in that The rotation speed control unit (11) increases or decreases the rotation speed of the internal combustion engine (1) at a plurality of different change rates according to the running speed of the vehicle driven by the motor generator (2).

5. The control device (100) for an internal combustion engine according to claim 4, characterized in that: The vehicle is a series hybrid vehicle that drives the motor generator (2) using the internal combustion engine (1) and drives an electric motor using the electric power generated by the motor generator (2).

Images