Control device for internal combustion engine

Abstract

To provide an internal combustion engine control device capable of preventing an ignition timing from being changed due to erroneous detection of knocking.SOLUTION: An internal combustion engine control device comprises: a detection section which detects knocking of an internal combustion engine; a first ignition timing control section which controls an ignition timing of the internal combustion engine through knock control system (KCS) learning in response to detection of the knocking by the detection section; a second ignition timing control section which performs knock correction of the ignition timing in response to the detection of the knocking by the detection section; a pressure control section which controls pressure of fuel; and a relief valve which opens when the pressure of the fuel becomes equal to or higher than first pressure. When the pressure control section increases a target value of the pressure of the fuel from the first pressure to certain pressure within a predetermined range, the internal combustion engine control device at least either causes the first ignition timing control section to stop the KCS learning or causes the second ignition timing control section to stop the knock correction for each of a plurality of cylinders.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

[0002] A technique for controlling ignition timing to suppress knocking in an internal combustion engine is known (for example, see Patent Document 1). When a sensor detects knocking, the ignition timing is retarded. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-327346 A Summary of the Invention [Problem to be solved by the invention]

[0004] A high-pressure fuel system that supplies fuel at high pressure is provided with a relief valve. Vibrations occur when the relief valve is opened and closed. A false detection may occur in which a sensor erroneously detects the vibrations as knocking. If the ignition timing is controlled in response to the false detection, the ignition timing may change. Therefore, an object of the present invention is to provide a control device for an internal combustion engine that is capable of suppressing changes in the ignition timing due to false detection of knocking. [Means for solving the problem]

[0005] The object of the present invention is to provide a detection unit that detects knocking of an internal combustion engine, a first ignition timing control unit that controls ignition timing in a plurality of cylinders of the internal combustion engine by KCS (Knock control system) learning in response to the detection unit detecting the knocking, and a second ignition timing control unit that controls ignition timing in the plurality of cylinders in response to the detection unit detecting the knocking. Separately forThe engine is provided with a second ignition timing control section that performs knock correction of the ignition timing, a pressure control section that controls the pressure of the fuel, and a relief valve that opens when the pressure of the fuel becomes equal to or higher than a first pressure, and the pressure control section When a target value of the pressure of the fuel is set to the first pressure and the pressure of the fuel is increased toward the first pressure, the first ignition timing control section teeth Stop KCS learning the KCS learning is a feedback control of the ignition timing, a feedback value is determined by the feedback control, the first ignition timing control unit performs the KCS learning to update the KCS learning value based on a KCS learning value and the feedback value, the first ignition timing control unit acquires a feedback smoothed value by smoothing the feedback value, and updates the KCS learning value based on the feedback smoothed value, when the pressure control unit increases the pressure of the fuel toward the first pressure, the first ignition timing control unit sets the feedback smoothed value to a predetermined value, and when the feedback smoothed value is the predetermined value, the first ignition timing control unit stops updating the KCS learning value. This can be achieved by controlling the internal combustion engine.

[0006] The pressure control unit Directing the pressure of the fuel toward the first pressure When the KCS is increased, the first ignition timing control section may stop the KCS learning, and the second ignition timing control section may stop the knock correction for each of the plurality of cylinders.

[0010] When the pressure of the fuel drops below a second pressure that is lower than the first pressure, the first ignition timing control unit may resume the KCS learning, or the second ignition timing control unit may resume knock correction for each of the multiple cylinders. Effect of the Invention

[0011] It is possible to provide a control device for an internal combustion engine that is capable of suppressing changes in ignition timing due to erroneous detection of knocking. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram illustrating an engine system. [Diagram 2] 2(a) and 2(b) are schematic diagrams illustrating the ignition timing. [Diagram 3] FIG. 3 is a diagram illustrating an example of a time chart. [Figure 4] FIG. 4 is a flowchart illustrating the processing executed by the ECU. [Diagram 5] FIG. 5 is a flowchart illustrating the processing executed by the ECU. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The control device for an internal combustion engine according to the present embodiment will now be described with reference to the drawings. Fig. 1 is a schematic diagram illustrating an engine system 100. The engine system 100 has an internal combustion engine 10 and an ECU (Electronic Control Unit) 40.

[0014] The internal combustion engine 10 is, for example, a gasoline engine fueled by gasoline, and is, for example, a four-cylinder engine having four cylinders 10a, 10b, 10c, and 10d. A spark plug 12a and a fuel injection valve 14a are provided in the cylinder 10a. A spark plug 12b and a fuel injection valve 14b are provided in the cylinder 10b. A spark plug 12c and a fuel injection valve 14c are provided in the cylinder 10c. A spark plug 12d and a fuel injection valve 14d are provided in the cylinder 10d. The knock sensor 26 is a sensor that detects vibrations and detects knocking of the internal combustion engine 10.

[0015] An intake passage 20 and an exhaust passage 30 are connected to the internal combustion engine 10. An air flow meter 22 and a throttle valve 24 are provided in the intake passage 20, in this order from the upstream side. The air flow meter 22 measures the flow rate of air. The throttle valve 24 adjusts the flow rate of air.

[0016] The intake passage 20 branches into four passages downstream of the throttle valve 24. The four branched passages are connected to the four cylinders 10a, 10b, 10c, and 10d of the internal combustion engine 10. Fuel injection valves 16a, 16b, 16c, and 16d are provided in the four branched intake passages 20. The four fuel injection valves 16a, 16b, 16c, and 16d are arranged corresponding to the four cylinders 10a, 10b, 10c, and 10d of the internal combustion engine 10.

[0017] The fuel injectors 14a, 14b, 14c, and 14d are connected to a delivery pipe 15. The fuel injectors 16a, 16b, 16c, and 16d are connected to a delivery pipe 17. The delivery pipe 15 is a low-pressure delivery pipe. The delivery pipe 17 is a high-pressure delivery pipe.

[0018] Fuel is stored in fuel tank 50. Pump 51 is a feed pump, and is disposed in fuel tank 50. One end of fuel path 52 is connected to pump 51. Two fuel paths 53 and 54 branch off from fuel path 52. Fuel path 54 is a high-pressure path. Fuel path 53 is connected to delivery pipe 15. Pump 55 is provided midway along fuel path 54. Fuel path 56 is connected to delivery pipe 17.

[0019] A pump 51 pumps out fuel from a fuel tank 50 and supplies it to a fuel path 52. The fuel is introduced from the fuel path 52 to fuel paths 53 and 54. The fuel flowing through the fuel path 53 is supplied to a delivery pipe 17. The fuel injectors 16a, 16b, 16c, and 16d inject the fuel supplied from the delivery pipe 17.

[0020] Pump 55 pressurizes fuel in fuel path 54. The high-pressure fuel is supplied from fuel path 54 to delivery pipe 15. Fuel injection valves 14a, 14b, 14c, and 14d inject the fuel supplied from delivery pipe 15. By directly injecting high-pressure fuel into the cylinders (direct injection), emissions can be improved.

[0021] The pressure sensor 57 is provided in the delivery pipe 15 and detects the pressure of the fuel in the delivery pipe 15. A relief valve 19 is provided in the delivery pipe 15. A fuel line 56 is connected to the relief valve 19 and extends from the relief valve 19 to the fuel tank 50.

[0022] When the pressure of the fuel in the delivery pipe 15 is less than a predetermined pressure (first pressure, valve opening pressure P1), the relief valve 19 is open. Fuel does not flow into the fuel path 56. When the pressure of the fuel in the delivery pipe 15 becomes equal to or greater than the predetermined pressure (first pressure, valve opening pressure P1), the relief valve 19 opens. The fuel flows out from the delivery pipe 15 into the fuel path 56 and returns to the fuel tank 50. The fuel path 56 is a relief path that allows the fuel to flow from the delivery pipe 15 to the fuel tank 50.

[0023] The exhaust passage 30 has four branched passages. These four passages are connected to the four cylinders 10a, 10b, 10c, and 10d of the internal combustion engine 10, and merge into one passage downstream. An air-fuel ratio sensor 36, a pressure sensor 32, an exhaust purification unit 38, and a pressure sensor 34 are provided in the exhaust passage 30 in this order from the upstream side. The air-fuel ratio sensor 36 detects the air-fuel ratio.

[0024] The exhaust purification unit 38 includes, for example, a GPF (Gasoline Particle Filter) and a catalyst. The GPF is, for example, a honeycomb filter that collects PM in the exhaust. The catalyst is, for example, a three-way catalyst that is coated on the wall surface of the GPF and purifies CO, NOx, and the like in the exhaust.

[0025] The pressure sensor 32 is provided upstream of the exhaust purification section 38 and detects the pressure in the exhaust passage 30 upstream of the exhaust purification section 38. The pressure sensor 34 is provided downstream of the exhaust purification section 38 and detects the pressure in the exhaust passage 30 downstream of the exhaust purification section 38. The internal combustion engine 10 may be provided with an EGR (Exhaust Gas Recirculation) device or the like.

[0026] The ECU 40 is a control device that includes a calculation device such as a CPU (Central Processing Unit), and storage devices such as a flash memory, a ROM (Read Only Memory), and a RAM (Random Access Memory), and performs various controls by executing programs stored in the storage devices.

[0027] The ECU 40 controls the opening of the throttle valve 24. The ECU 40 obtains the air flow rate from the air flow meter 22, the air-fuel ratio from the air-fuel ratio sensor 36, the pressure upstream of the exhaust purification unit 38 from the pressure sensor 32, and the pressure downstream of the exhaust purification unit 38 from the pressure sensor 34. The ECU 40 calculates the pressure difference between the upstream side and the downstream side of the exhaust purification unit 38 as the difference between the pressure detected by the pressure sensor 32 and the pressure detected by the pressure sensor 34. The ECU 40 obtains the pressure of the fuel detected by the pressure sensor 57. The ECU 40 functions as a pressure control unit that controls the pressure of the fuel (fuel pressure) in the delivery pipe 15 by controlling the pump 55. For example, the ECU 40 determines a target value of the fuel pressure, and drives the pump 55 so that the fuel pressure becomes the target value.

[0028] The ECU 40 detects knocking by acquiring a signal output by the knock sensor 26. For example, the ECU 40 acquires the frequency of knocking for each cylinder based on the combustion timing and the knocking timing for each cylinder.

[0029] The ECU 40 functions as a fuel control unit that controls the supply of fuel from each of the fuel injection valves 14a to 14d and controls the supply of fuel from each of the fuel injection valves 16a to 16d. The ECU 40 can stop the injection of fuel to at least one of the four cylinders (fuel cut). During fuel cut, exhaust gas containing more oxygen is discharged from the cylinder compared to when fuel is supplied. By introducing more oxygen into the exhaust purification unit 38, PM is oxidized and removed.

[0030] The ECU 40 controls the on / off of ignition by each of the spark plugs 12a to 12d and the ignition timing. The control of the ignition timing includes KCS (Knock control system) learning and cylinder-specific knock correction. The KCS learning is feedback control of the ignition timing of the spark plugs 12a, 12b, 12c, and 12d. For example, when knocking occurs, the ignition timing of the four spark plugs is retarded. When knocking stops, the ignition timing of the four spark plugs is advanced. The KCS learning controls the ignition timing of all four spark plugs. On the other hand, the cylinder-specific knock correction controls the ignition timing of the spark plugs of the four cylinders individually. The ECU 40 functions as a first ignition timing control unit that controls the ignition timing of all four cylinders 10a to 10d based on the KCS learning. The ECU 40 functions as a second ignition timing control unit that controls the ignition timing for each cylinder. By retarding the ignition timing, knocking can be suppressed. By advancing the ignition timing, the output of the internal combustion engine 10 can be improved.

[0031] Figures 2(a) and 2(b) are schematic diagrams illustrating ignition timing, showing an example of ignition timing determination by KCS learning. The upper side in the figure is the advance side, and the lower side is the retard side. KCS learning uses a KCS learning value and a feedback value (F / B value). Figure 2(a) is an example where the F / B value is F / B1. Figure 2(b) is an example where the F / B value is F / B2.

[0032] Bkcs is the base ignition timing, which is determined, for example, by the operating range (rotation speed, load, etc.) of the internal combustion engine 10, the timing and amount of fuel injection, the amount of EGR, etc. Rmax is the most retarded ignition timing, which is determined, for example, by the vehicle type, etc. A0, A1 in FIG. 2(a), and A2 in FIG. 2(b) are KCS learning values. The KCS learning value changes as KCS learning is performed. In the examples of FIG. 2(a) and FIG. 2(b), the initial value of the KCS learning value is A0. In the example of FIG. 2(a), the KCS learning value is updated from A0 to A1, which is more retarded than A0. In the example of FIG. 2(b), the KCS learning value is updated from A0 to A2, which is more advanced than A0.

[0033] F / B0 is the limit of the F / B value on the advance side, for example 0° CA (Crank Angle). The F / B value can take on values ​​ranging from F / B0 to Rmax. F / Bi is the initial value of the F / B value, a value that is more retarded than F / B0 and more advanced than Rmax, for example -3° CA.

[0034] 2(a) is an example of an F / B value, which is more retarded than F / Bi. Akcs is the required ignition timing. The ECU 40 calculates the required ignition timing Akcs using the following equation. Akcs=Bkcs-Rmax+A0-F / B1

[0035] The F / B value F / B2 in Fig. 2(b) is more advanced than the F / B1 in Fig. 2(a). The ECU 40 calculates the required ignition timing Akcs using the following equation. Akcs=Bkcs-Rmax+A0-F / B2 The required ignition timing Akcs calculated using F / B2 is more advanced than Akcs in FIG. 2(a).

[0036] The KCS learning is performed for all four cylinders 10a, 10b, 10c, and 10d, i.e., the ignition timings of the four cylinders 10a, 10b, 10c, and 10d become the required ignition timings Akcs.

[0037] When the knock sensor 26 detects knocking, the ECU 40 retards the required ignition timing Akcs by setting the F / B value to a more retarded side than F / Bi, such as F / B1 in Fig. 2(a).When knocking is not detected, the ECU 40 advances the required ignition timing Akcs by setting the F / B value to a more advanced side than F / Bi, such as F / B2 in Fig. 2(b).

[0038] The ECU 40 obtains the F / B smoothed value by smoothing the F / B value. When knocking occurs, the F / B value is retarded and the F / B smoothed value is also retarded. When knocking stops, the F / B value is advanced and the F / B smoothed value is also advanced. The ECU 40 determines whether or not to update the KCS learning value based on the F / B smoothed value.

[0039] In the example of Fig. 2(a), F / B1 is more retarded than F / Bi (-3° CA). If the F / B smoothing value obtained from F / B1 is more retarded than, for example, -4° CA, the ECU 40 retards the KCS learning value from A0 to A1. The ECU 40 retards the ignition timing using the updated KCS learning value A1.

[0040] In the example of Fig. 2(b), F / B2 is more advanced than F / Bi (-3° CA). If the F / B smoothing value obtained from F / B2 is more advanced than -2° CA, for example, the ECU 40 advances the KCS learning value from A0 to A2. The ECU 40 advances the ignition timing using the updated KCS learning value A2.

[0041] In cylinder-specific knock correction, the ignition timing is controlled according to the frequency of knocking for each cylinder. The frequency of knocking is measured by the ECU 40. For example, if knocking is detected by the knock sensor 26 immediately after ignition in cylinder 10a, it is assumed that knocking has occurred in cylinder 10a, and the knocking frequency of cylinder 10a is added. The ignition timing of a cylinder with a high frequency of knocking is retarded. The ignition timing of a cylinder with a low frequency of knocking is advanced. Table 1 shows an example of the frequency of knocking for each cylinder and the correction value for cylinder-specific knock correction. The correction value is the amount by which the ignition timing is advanced or retarded. [Table 1]

[0042] As shown in Table 1, the knocking frequency of cylinder 10a is n1 and the correction value is k1. The knocking frequency of cylinder 10b is n2 and the correction value is k2. The knocking frequency of cylinder 10c is n3 and the correction value is k3. The knocking frequency of cylinder 10d is n4 and the correction value is k4.

[0043] For example, if the knocking frequency n3 of the cylinder 10c is a predetermined number of times or more higher than the knocking frequencies of the other cylinders, the ECU 40 sets the correction value k3 to a value that is more retarded than the other correction values. The predetermined number of times may be once or more. The ignition timing of the cylinder 10c can be retarded by adding the correction value k3 to the ignition timing Akcs obtained by KCS learning. In the example of FIG. 2(a), when performing cylinder-specific knock correction and retarding the ignition timing of the cylinder 10c, the ignition timing is calculated, for example, by the following formula. Akcs=Bkcs-Rmax+A0-F / B1+k3

[0044] For example, if the knocking frequency n4 of cylinder 10d is lower than the knocking frequencies of the other cylinders, ECU 40 sets correction value k4 to a value that is more advanced than the other correction values. By adding correction value k4 to the ignition timing Akcs obtained by KCS learning, it is possible to advance the ignition timing of cylinder 10d. For example, if the knocking frequencies of two or more cylinders are equal, ECU 40 sets the correction values ​​of the two or more cylinders to be equal. Knocking can be suppressed by the above-mentioned KCS learning and cylinder-specific knock correction.

[0045] The ECU 40 controls the operation of the pump 55 to control the pressure of the fuel in the delivery pipe 15. The ECU 40 determines a target value (target fuel pressure P0) of the fuel pressure in the delivery pipe 15, and drives the pump 55 so that the fuel pressure becomes the target fuel pressure P0. The ECU 40 obtains pressure from a pressure sensor 57, and checks the rationality of the pressure sensor 57.

[0046] 3 is a diagram illustrating an example of a time chart, which shows, from the top, the fuel pressure, the hitting flag, the KCS learning flag, and the individual cylinder knock correction flag.

[0047] P0 is a target value (target fuel pressure) of the fuel pressure in the delivery pipe 15, and is determined by the ECU 40. P3 is the actual fuel pressure in the delivery pipe 15, and is the pressure detected by the pressure sensor 57. P1 is the opening pressure of the relief valve 19. The pressures P2 and P4 are, for example, 5 MPa.

[0048] The target fuel pressure P0 before time t1 is P5, which is lower than the valve opening pressure P1. At time t1, the ECU 40 sets the target fuel pressure P0 to the valve opening pressure P1. In response to setting the target fuel pressure P0 to P1, the ECU 40 drives the pump 55 to increase the fuel pressure P3. The fuel pressure P3 changes with a delay from the target fuel pressure P0, and rises to the valve opening pressure P1 at time t2. At time t3, the ECU 40 sets the target fuel pressure P0 to P5. The fuel pressure P3 decreases, and at time t4, it decreases to a pressure (P5+P4, the second pressure) that is higher than the pressure P5 by P4.

[0049] Before time t1, the hitting flag is off, and the KCS learning flag and the individual cylinder knock correction flag are on. At time t1, the hitting flag is turned on. The KCS learning flag and the individual cylinder knock correction flag are turned off. During the period from time t1 to t4, the hitting flag is on. The ECU 40 acquires pressure P3 detected by pressure sensor 57 and compares it with valve opening pressure P1 (thrust control) to diagnose rationality. If pressure P3 falls within a predetermined range centered on valve opening pressure P1, for example, it is confirmed that pressure sensor 57 is normal.

[0050] During the rationality check, the fuel pressure rises to the valve opening pressure P1 and then falls from the valve opening pressure P1, so that the relief valve 19 opens and closes. Vibrations occur when the relief valve 19 opens and closes. The knock sensor 26 may erroneously detect the vibrations caused by the opening and closing of the relief valve 19 as knocking. If the KCS learning and the cylinder-specific knock correction are performed based on the erroneous detection, the ignition timing may change. Specifically, the ignition timing may be excessively retarded, and the output of the internal combustion engine 10 may decrease. As shown in FIG. 3, the KCS learning flag and the cylinder-specific knock correction flag are OFF during the period from time t1 to t4. In this embodiment, the KCS learning and the cylinder-specific knock correction are stopped to suppress the change in the ignition timing caused by the erroneous detection.

[0051] 4 and 5 are flow charts illustrating processing executed by the ECU 40. The ECU 40 determines whether the target fuel pressure P0 is equal to or greater than a pressure within a predetermined range from the opening pressure P1 of the relief valve 19, for example, a pressure (P1-P2) lower than P1 by P2 (step S10). If the determination is affirmative (Yes), the ECU 40 turns on the butting flag (step S12). If the butting flag is on, the ECU 40 performs butting control and checks the rationality of the pressure sensor 57. After step S12, the process proceeds to step S18.

[0052] If the determination in step S10 is negative (No), the ECU 40 determines whether the target fuel pressure P0 is lower than the valve opening pressure P1 and whether the measured value P3 of the pressure sensor 57 is less than a pressure (P5+P4) that is higher than P5 by P4 (step S14). If the determination is positive, the ECU 40 turns off the hitting flag (step S16). If the determination in step S14 is negative or after step S16, the process proceeds to step S18.

[0053] The ECU 40 determines whether or not knocking is occurring based on a signal input from the knock sensor 26, etc. (step S18). If the determination is positive, the ECU 40 corrects the F / B value to the retard side (step S20). If the determination is negative, the ECU 40 corrects the F / B value to the advance side (step S22). After step S20 or S24, the process proceeds to step S24.

[0054] The ECU 40 determines whether the butting flag is off (step S24 in FIG. 5). If the determination is negative, the ECU 40 initializes the F / B smoothed value and sets it to an initial value of −3° CA (step S26). If the determination is positive, the ECU 40 smooths the F / B value to calculate the F / B smoothed value (step S28).

[0055] The ECU 40 determines whether the F / B smoothed value acquired in step S26 or S28 is less than -4° CA (on the retard side) or whether the F / B smoothed value is greater than -2° CA (on the advance side) (step S30). If the determination is positive, the ECU 40 performs KCS learning and updates the KCS learning value (step S32). If the determination is negative, the ECU 40 stops KCS learning (step S34). By stopping KCS learning, the KCS learning value is not updated.

[0056] The ECU 40 determines whether the hitting flag is off (step S36). If the determination is affirmative, the ECU 40 performs the individual cylinder knock correction (step S38). If the determination is negative, the ECU 40 stops the individual cylinder knock correction (step S40). After step S38 or S40, the process ends.

[0057] According to this embodiment, during the period when the butting flag is on (from time t1 to t4 in FIG. 3), the ECU 40 increases the fuel pressure to the valve opening pressure P1 and decreases it from the valve opening pressure P1, and performs a rationality check of the pressure sensor 57. The ECU 40 stops KCS learning and stops cylinder-specific knock correction (steps S34 and S40 in FIG. 5). There is a risk that vibrations caused by the opening and closing of the relief valve 19 will be erroneously detected as knocking by the knock sensor 26. Even if an erroneous detection occurs, a change in the ignition timing is suppressed by stopping the KCS learning and the cylinder-specific knock correction. Since the ignition timing is unlikely to be retarded, a decrease in the output of the internal combustion engine 10 is suppressed.

[0058] As shown in Fig. 2(a) and Fig. 2(b), the ECU 40 performs KCS learning based on the KCS learning value and the F / B value. If KCS learning is performed during a rationality check of the pressure sensor 57, the KCS learning value may be retarded to A1 or the like, as in the example of Fig. 2(a). According to this embodiment, the update of the KCS learning value is stopped. The retardation of the KCS learning value is suppressed, and the KCS learning value maintains the value before the start of the rationality check. Since the KCS learning value is not retarded, the retardation of the ignition timing is suppressed. As a result, a decrease in output is suppressed.

[0059] The ECU 40 corrects the ignition timing according to the frequency of knocking for each cylinder (cylinder-specific knock correction, Table 1). While detecting rationality, the ECU 40 stops the cylinder-specific knock correction. By stopping the cylinder-specific knock correction, the retardation of the correction value shown in Table 1 is suppressed. By suppressing the retardation of the correction value, the retardation of the ignition timing is suppressed. Therefore, the reduction in output is suppressed.

[0060] The ECU 40 may perform at least one of stopping the KCS learning and stopping the cylinder-specific knock correction. This suppresses the retardation of the ignition timing and suppresses the decrease in output. By performing both the stopping of the KCS learning and the cylinder-specific knock correction as shown in Figures 4 and 5, it is possible to suppress the retardation of the ignition timing and suppress the decrease in torque more effectively.

[0061] Even during a rationality check, it is possible to retard and advance the F / B value (steps S20 and S22 in FIG. 4). By retarding the F / B, the ignition timing is retarded and knocking can be suppressed. If knocking is not detected, the F / B value is advanced. The F / B value is updated more quickly than the KCS learning value. By quickly updating the F / B value in response to knocking, the ignition timing is appropriately adjusted. Knocking can be suppressed and a decrease in output due to excessive retardation can also be suppressed.

[0062] The ECU 40 obtains an F / B smoothed value by smoothing the F / B value. When performing the bumping control, the F / B smoothed value is set to a predetermined value (for example, -3° CA). If the F / B smoothed value is -3° CA, a negative determination is made in step S30, and the ECU 40 stops the KCS learning and does not update the KCS learning value (step S34 in FIG. 5). This makes it possible to suppress changes in the ignition timing.

[0063] During the rationality check, the F / B value may be advanced or retarded (steps S20 and S22 in FIG. 4). When the F / B smoothed value is calculated from the F / B value, the F / B smoothed value is also advanced or retarded. If the KCS learning value is updated based on the F / B smoothed value after the rationality check is completed, the KCS learning value will change. For example, if the F / B smoothed value is retarded, the KCS learning value will be retarded after the start of KCS learning. According to this embodiment, the F / B smoothed value during the rationality check is set to a predetermined value (e.g., -3° CA). At the start of KCS learning, the F / B smoothed value is, for example, -3° CA. It is possible to suppress erroneous learning of the KCS learning value. It is possible to suppress retardation of the KCS learning value and suppress a decrease in torque.

[0064] When pressure P3 drops from valve opening pressure P1, direct injection is performed by fuel injection valves 14a, 14b, 14c, and 14d, and port injection is not performed. There is a risk that vibrations caused by opening and closing of the fuel injection valves may be erroneously detected as knocking by knock sensor 26. Therefore, when pressure P3 is equal to or greater than pressure P5+P4, the hitting flag is not turned off but remains on (negative determination in step S14 in FIG. 4). ECU 40 stops KCS learning and cylinder-specific knock correction (steps S34, S40 in FIG. 5). Changes in ignition timing are suppressed. After pressure P3 drops below pressure P5+P4, ECU 40 resumes KCS learning and cylinder-specific knock correction.

[0065] The number of cylinders in the internal combustion engine 10 may be four or less, or may be four or more. The number of fuel injectors is changed according to the number of cylinders.

[0066] Although a preferred embodiment of the present invention has been described in detail above, the present invention is not limited to such a specific embodiment, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0067] 10 Internal combustion engine 10a, 10b, 10c, 10d cylinders 12a, 12b, 12c, 12d Spark plugs 14a, 14b, 14c, 14d, 16a, 16b, 16c, 16d Fuel injector 20 Intake passage 22 Air flow meter 24 Throttle valve 30 Exhaust passage 32, 34 Pressure sensor 36 Air-fuel ratio sensor 38 Exhaust purification section 40 ECU 100 Engine System

Claims

1. A detection unit for detecting knocking of an internal combustion engine; a first ignition timing control unit that controls ignition timings in a plurality of cylinders of the internal combustion engine by KCS (Knock control system) learning in response to the detection unit detecting the knocking; a second ignition timing control unit that performs knock correction of ignition timing individually for the plurality of cylinders in response to the detection unit detecting the knocking; A pressure control unit that controls the pressure of the fuel; a relief valve that opens when the pressure of the fuel becomes equal to or higher than a first pressure, When the pressure control unit sets a target value of the pressure of the fuel to the first pressure and increases the pressure of the fuel toward the first pressure, the first ignition timing control unit stops the KCS learning, The KCS learning is a feedback control of the ignition timing, The feedback value is determined by the feedback control, the first ignition timing control unit performs the KCS learning to update the KCS learning value based on a KCS learning value and the feedback value; The first ignition timing control unit smoothes the feedback value to obtain a feedback smoothed value, and updates the KCS learning value based on the feedback smoothed value; When the pressure control unit increases the pressure of the fuel toward the first pressure, the first ignition timing control unit sets the feedback smoothing value to a predetermined value, A control device for an internal combustion engine, wherein the first ignition timing control unit stops updating the KCS learning value when the feedback smoothing value is the predetermined value.

2. 2. The control device for an internal combustion engine according to claim 1, wherein, when the pressure control unit increases the fuel pressure toward the first pressure, the first ignition timing control unit stops the KCS learning, and the second ignition timing control unit stops knock correction for each of the plurality of cylinders.

3. 3. The control device for an internal combustion engine according to claim 2, wherein, when the pressure of the fuel drops to less than a second pressure that is lower than the first pressure, the first ignition timing control unit resumes the KCS learning, or the second ignition timing control unit resumes the knock correction for each of the plurality of cylinders.

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