JP6453021B2 - Ignition timing control device and control method - Google Patents

Description

  The present invention relates to an ignition timing control device and a control method for controlling an ignition timing of an air-fuel mixture.

  Conventionally, in an engine using gasoline or natural gas as fuel, the ignition timing is controlled according to the operating state of the engine. The ignition timing control device has an ignition map in which a base ignition timing corresponding to the operating state of the engine is defined, and controls the ignition timing to a target ignition timing calculated based on the operating state of the engine and the ignition map. Regarding the control of the ignition timing, Patent Document 1 discloses a technique for advancing the target ignition timing periodically (for example, every second) and retarding the target ignition timing when knocking is detected by a knock sensor. Has been.

JP-A-8-135487

  Incidentally, the appropriate margin of the target ignition timing with respect to the knock ignition timing at which knocking is likely to occur is often different depending on the operating state of the engine. In this regard, in Patent Document 1, the amount of retardation associated with the detection of knocking is a constant value. Therefore, there is a possibility that knocking is likely to occur due to an insufficient margin with respect to the knock ignition timing due to an insufficient retard amount.

  An object of the present invention is to provide an ignition timing control device and control method capable of suppressing the occurrence of knocking.

An ignition timing control device that solves the above-mentioned problems is provided with a knock detection unit that detects knocking for each of a plurality of cylinders constituting an engine, and a base ignition timing that is an ignition timing according to the operating state of the engine. Each of the cylinders is provided with a storage unit that stores an ignition map and a margin map in which a margin from the ignition timing at which the knocking is detected is defined as a value corresponding to the operating state at which the knocking is detected. An ignition timing control unit for separately controlling the ignition timing of the spark plug, wherein the ignition timing of the ignition plug is set to a target ignition timing that is an ignition timing based on the base ignition timing and a correction amount for the base ignition timing. and a said ignition timing control unit for controlling said for each of the plurality of spark plugs
A correction amount storage unit that stores correction amounts separately, an update target detection unit that detects an update target that is a specific spark plug that updates the correction amount from among the plurality of spark plugs, and an exhaust passage of the engine An air-fuel ratio calculation unit that calculates the air-fuel ratio of each of the plurality of cylinders of the engine based on the detection value of the provided air-fuel ratio sensor, and the ignition timing control unit includes the update target detection unit When the update target is detected, each time the update target is set as a drive target until the knock detection unit detects knocking of the cylinder corresponding to the update target, the ignition timing of the update target is incremented by a predetermined amount from the target ignition timing. advance is angularly, with knocking in the cylinder corresponding to the update target is to obtain the advance amount before detection, in cylinders in which the knocking detection unit corresponding to the update target When the operating state when the detecting knocking the Tokushi preparative the margin in accordance with the operating condition by applying to the margin map, the obtained margin is greater than the advance amount with the acquired, the correction amount update the correction amount of the update target storage unit is storing in a direction amount corresponding ignition timing is retarded in the first update amount which is a difference between the acquired margin and the obtained advance amount, the The update target detection unit calculates an average value of air-fuel ratios for all cylinders when the engine is in a steady state, and an absolute value of a deviation between the calculated average value and the air-fuel ratio for each cylinder is a threshold value. Spark plugs corresponding to the above cylinders are detected as the update target.

An ignition timing control method that solves the above-described problem is a spark plug ignition timing that is set to a target ignition timing that is an ignition timing based on a base ignition timing that is an ignition timing according to an operating state of the engine and a correction amount for the base ignition timing. The ignition timing control method for controlling the ignition timing, wherein the control device for controlling the ignition timing separately controls the ignition timing of a spark plug provided for each of a plurality of cylinders constituting the engine, and knocking A storage unit that stores a margin map in which a margin from the detected ignition timing is defined as a value corresponding to the operating state in which knocking is detected; and the correction amount for each of the plurality of spark plugs. A correction amount storage unit that stores the air-fuel ratio provided in the exhaust passage of the engine when the engine is in a steady state. An average value of the air-fuel ratio for all cylinders is calculated based on the detection value of the sensor, and a specific spark plug corresponding to a cylinder whose absolute value of the deviation between the calculated average value and the air-fuel ratio for each cylinder is equal to or greater than a threshold value When the update target is detected and the update target is set as the drive target, the ignition timing of the update target is advanced by a predetermined amount from the target ignition timing to detect knocking of the cylinder corresponding to the update target. obtains the advance amount of up to, advance angle by applying the operating state to the margin map Tokushi preparative margin in accordance with the operating condition, said acquired margins and the acquisition of when the knocking is detected when greater than the amount, the correction amount first update amount of amount corresponding ignition storage unit is a difference between the acquired margin and the obtained advance amount to the correction amount of the subject to update stored To update in the direction in which the retarded.

  According to the above configuration, since the margin is selected according to the operating state of the engine when knocking is detected, it is possible to suppress the margin from being insufficient. As a result, occurrence of knocking can be suppressed.

  As in the above configuration, when the engine is in a steady state, each spark plug is driven under approximately the same conditions. Therefore, by detecting an update target in a steady state, a spark plug whose correction amount is to be updated is detected with high accuracy.

Differences in ignition timing between different spark plugs are reflected in the air-fuel ratio. Therefore, it is possible to detect the update target based on the air-fuel ratio as in the above configuration.
The ignition timing control device further includes an output calculation unit that calculates an output for each cylinder, and the ignition timing control unit updates the correction amount of the update target stored in the correction amount storage unit in the first update. updating amount of minute only, on the condition that the operating state of the engine is in a steady state, the updated object based on the correction amount after updating the ignition timing of the update target, each time setting a driving target the target ignition with retarding by a predetermined amount from the time the update subject Tokushi preparative output of cylinder corresponding to the update target each time it is driven, the last acquired output said updated with the driving of the update target When the output becomes smaller than the output acquired with the drive immediately before the most recent drive, the correction amount stored in the correction amount storage unit is the retardation amount with respect to the target ignition timing. To update the second update of an amount corresponding direction ignition timing is retarded a retardation amount during the preceding drive Te is preferred.

  According to the above configuration, the target ignition timing can be controlled to an ignition timing at which the output of the cylinder corresponding to the update target is maximized while ensuring a margin for the knock ignition timing.

It is a figure which shows schematic structure of the engine system carrying the ignition timing control apparatus of one Embodiment. It is a figure which shows an example of a margin map. It is a flowchart which shows an example of an update process. It is a figure which shows an example of the relationship between target ignition timing and actual ignition timing.

  An embodiment of an ignition timing control device and control method will be described with reference to FIGS. With reference to FIG. 1, an overall configuration of an engine system in which an ignition timing control device is mounted will be described.

  As shown in FIG. 1, the engine 10 of the engine system has six cylinders 12 in a cylinder block 11. The engine 10 is an MPI (Multi Point Injection) engine and has a spark plug 13 for each cylinder 12 for igniting an air-fuel mixture in the cylinder 12. The spark plug 13 is, for example, a spark plug that electrically generates a spark. An intake manifold 14 for supplying intake air to each cylinder 12 and an exhaust manifold 15 into which exhaust gas from each cylinder 12 flows are connected to the cylinder block 11.

  In the intake passage 16 connected to the intake manifold 14, an air cleaner (not shown), a compressor 18 constituting a turbocharger 17, an intercooler 19, a throttle valve 20, and a surge tank 21 are provided in order from the upstream side. The exhaust passage 25 connected to the exhaust manifold 15 is provided with a turbine 26 that is connected to the compressor 18 via a connecting shaft and constitutes the turbocharger 17.

  The engine system includes an intake air amount sensor 30, an intake pressure sensor 31, an intake air temperature sensor 32, a crank angle sensor 34, a cam angle sensor 35, an air-fuel ratio sensor 36, a cooling water temperature sensor 37, an accelerator opening sensor 38, a knock sensor 39, A combustion pressure sensor 40 is provided.

  The intake air amount sensor 30 detects an intake air amount Qa that is a volume flow rate of intake air flowing through the intake passage 16 upstream of the compressor 18 in the intake passage 16. The intake pressure sensor 31 detects an intake pressure Pb that is the pressure of intake air in the surge tank 21. The intake air temperature sensor 32 detects an intake air temperature Ti that is the temperature of intake air in the surge tank 21. The crank angle sensor 34 detects a crank angle CA that is a rotation angle of the crankshaft 10a. The cam angle sensor 35 outputs a cylinder discrimination signal G at a timing when a predetermined cylinder 12 reaches the compression top dead center based on a rotation angle of a camshaft (not shown). The air-fuel ratio sensor 36 detects an air-fuel ratio AF, which is a ratio of the weight of air to the weight of fuel in the mixture based on the oxygen concentration contained in the exhaust gas flowing out from the turbine 26. The cooling water temperature sensor 37 detects a cooling water temperature Tw that is the temperature of the cooling water that cools the engine 10. The accelerator opening sensor 38 detects an accelerator opening ACC that is a depression amount of the accelerator pedal 41. Knock sensor 39 is a resonance type or non-resonance type knock sensor, and detects knock information for detecting whether or not knocking has occurred in engine 10. The combustion pressure sensor 40 is provided for each cylinder 12 and detects the combustion pressure Pc of the corresponding cylinder 12. The signals output from the sensors 30 to 40 are input to a control device 50 that controls the ignition timing of each spark plug 13.

  The control device 50 is mainly configured by a microcomputer having a CPU, a ROM in which various control programs and various data are stored, and a RAM in which various calculation results and various data are temporarily stored. The control device 50 includes an acquisition unit 51 that acquires various types of information based on signals from each sensor, a processing unit 52 that executes various types of processing, and a memory that stores various types of control programs and various types of data including ROM and RAM. Unit 53. The processing unit 52 executes various processes based on various control programs stored in the storage unit 53 and information input from the sensors 30 to 40. The processing unit 52 functions as a knocking detection unit, an ignition timing control unit, an update target detection unit, an air-fuel ratio calculation unit, and an output calculation unit.

  Based on the signals from the various sensors, the acquisition unit 51 receives the intake air amount Qa, the intake pressure Pb, the intake air temperature Ti, the crank angle CA, the cylinder discrimination signal G, the air-fuel ratio AF, the accelerator opening ACC, the knock information, The combustion pressure Pc is acquired. The acquisition unit 51 acquires the engine speed Ne, which is the rotation speed of the crankshaft 10a, based on the crank angle CA.

  The storage unit 53 stores an ignition map 55 as various data. The ignition map 55 is an ignition timing corresponding to the engine speed Ne and the engine load L, and is data in which a base ignition timing Abse common to all the cylinders 12 is defined. The base ignition timing Abse is, by design, an ignition timing at which a predetermined margin Amar is ensured for knocking in each cylinder 12 and an ignition timing at which the torque value Trq is maximized. The engine load L is calculated based on, for example, the engine speed Ne, the accelerator opening ACC, the intake air amount Qa, the intake pressure Pb, the intake temperature Ti, and the like. It is assumed that the ignition timing is indicated by BTDC (Before Top Dead Center).

  The storage unit 53 as a correction amount storage unit stores correction amount data 56 as various data. The correction amount data 56 is data in which a correction amount Acom for the base ignition timing Abse is defined for each cylinder 12.

  The storage unit 53 stores, as various data, a margin map 57 in which a margin Amar, which is a margin of the ignition timing with respect to the knock ignition timing Aknk that occurs with a high probability of knocking, is defined. The margin map 57 will be described later.

Based on the cylinder discrimination signal G and the crank angle CA, the processing unit 52 sets a drive target that is the spark plug 13 corresponding to the cylinder 12 that burns the air-fuel mixture. The processing unit 52 sets a target ignition timing Atar to be driven, and drives the drive target at the set target ignition timing Atar. The processing unit 52 corrects the base ignition timing Abse based on the engine speed Ne, the engine load L, and the ignition map 55 by the correction amount Acom corresponding to the drive target, as in the following formula (1). To set the target ignition timing Atar.
Atar = Abse + Acom (1)

  Since the ignition timing is indicated by BTDC, in the correction amount Acom, the advance amount with respect to the base ignition timing Abse is indicated with a positive value, and the retardation amount with respect to the base ignition timing Abse is indicated with a negative value. The correction amount Acom may be a constant value regardless of the operating state of the engine 10 or may be a value selected based on the operating state of the engine 10.

  The processing unit 52 calculates the torque value Trq of the cylinder 12 corresponding to the drive target as the output of the cylinder 12. For example, based on the crank angle CA and the combustion pressure Pc, the processing unit 52 calculates the torque value Trq by substituting the combustion pressure Pc at the predetermined crank angle CA into a predetermined relational expression.

  Based on the cylinder discrimination signal G, the crank angle CA, and the knock information, the processing unit 52 detects whether knocking has occurred in the cylinder 12 corresponding to the spark plug 13 to be driven. When knock sensor 39 is a resonance type, the knock information indicates whether or not knocking has occurred in engine 10. When knock sensor 39 is non-resonant, the knock information indicates the frequency and amplitude of vibration of engine 10.

  The processing unit 52 calculates the air-fuel ratio AF of each cylinder 12. The processing unit 52 calculates the timing at which the exhaust gas discharged from the cylinder 12 reaches the air-fuel ratio sensor 36 for each cylinder 12 based on the cylinder discrimination signal G and the crank angle CA. The processing unit 52 calculates the air-fuel ratio AF of each cylinder 12 based on the signal from the air-fuel ratio sensor 36 at that timing.

  The processing unit 52 executes update processing for updating the correction amount Acom of the correction amount data 56 described above. In the update process, the processing unit 52 detects the update target that is the spark plug 13 whose target ignition timing Atar is to be updated, that is, the spark plug 13 whose update amount Acom is to be updated, and sets the detected correction amount Acom for the update target. Update.

  The processing unit 52 detects an update target when the warm-up of the engine 10 is completed and the operation state of the engine 10 is in a steady state. The processing unit 52 determines that the warm-up has been completed on condition that the coolant temperature Tw is equal to or higher than the warm-up completion temperature Tw1, which is a temperature at which it is determined that the engine 10 has been warmed up. The steady state is a state in which the fluctuation of the engine load L is small. For example, the engine speed Ne, the accelerator opening ACC, the intake air amount Qa, the intake pressure Pb, and the intake temperature Ti are substantially constant. The processing unit 52 detects the spark plug 13 corresponding to the cylinder 12 that is most likely to knock among the plurality of cylinders 12 as an update target. For example, the processing unit 52, based on the fact that the closer the air-fuel ratio AF is to the stoichiometric air-fuel ratio AFst in a steady state, the more likely knocking occurs. The spark plug 13 corresponding to the cylinder 12 for which is obtained is detected as an update target.

  The processing unit 52 that has detected the update target drives the drive target at the target ignition timing Atar when the spark plug 13 that is not the update target is set as the drive target. On the other hand, when the spark plug 13 to be updated is set as the drive target, the processing unit 52 drives the drive target at the temporary target ignition timing Atst in order to update the correction amount Acom.

The processing unit 52 updates the correction amount Acom related to knocking for the update target. The processing unit 52 sets the advance amount Aad, for example, 0.5 °, for the target ignition timing Atar every time the update target is set as the drive target until knocking is detected in the cylinder 12 corresponding to the update target. The update target is driven at the temporary target ignition timing Atsti advanced by CA. That is, the temporary target ignition timing Atsti is expressed by the following equation (2).
Atsti = Atar + Aad × i (2)

  “I” in the above formula (2) is a numerical value that is incremented every time the update target is set as the drive target, with i = 1 being the initial value. The set advance amount Aad is preferably such that the driver cannot feel that the ignition timing of the drive target has been advanced.

  When detecting the knocking in the cylinder 12 corresponding to the spark plug 13 to be updated, the processing unit 52 calculates the advance amount SAad (= Aad × i) until the knocking is detected. In other words, the advance amount SAad is a difference between the temporary target ignition timing Atsti when knocking is detected and the target ignition timing Atar when calculating the temporary target ignition timing Atsti. Then, the processing unit 52 calculates the first update amount Arev1 based on the advance amount SAad and the margin Amar defined in the margin map 57 stored in the storage unit 53.

  As shown in FIG. 2, the margin map 57 is data in which a margin Amar is defined according to the engine speed Ne and the engine load L. The margin Amar is the amount of retardation required for the knock ignition timing Aknk in order to suppress the occurrence of knocking with a high probability in the operating state of the engine speed Ne and the engine load L.

  The processing unit 52 calculates the first update amount Arev1 by subtracting the margin Amar from the advance amount SAad. The processing unit 52 retards the correction amount Acom by the amount of the first update amount Arev1 when the first update amount Arev1 is a negative value, and the first update amount Arev1 when the first update amount Arev1 is a positive value. The correction amount Acom is advanced by an amount corresponding to one update amount Arev1. Then, the processing unit 52 updates the correction amount Acom to be updated by storing the new correction amount Acom in a predetermined area of the storage unit 53.

  In addition, the processing unit 52 updates the correction amount Acom related to the output of the engine 10. The correction amount Acom is updated on condition that the operating state of the engine 10 is in a steady state. Therefore, when the operating state of the engine 10 shifts from the steady state to another operating state, the processing unit 52 ends the updating process without updating the correction amount Acom related to the output.

The processing unit 52 calculates the target ignition timing Atar with the correction amount Acom updated for knocking. The processing unit 52 sets the target ignition timing Atar as the initial ignition timing, and each time the update target is set as the drive target, the temporary target ignition timing Atstj delayed by the set retard amount Art, for example, 0.5 ° CA. Is set to the ignition timing. That is, in updating the correction amount Acom related to the output, the temporary target ignition timing Atstj is expressed by the following equation (3).
Atstj = Atar−Art × (j−1) (3)

  “J” in Expression (3) is a numerical value that is incremented every time an update target is set as a drive target, with j = 1 as an initial value. The set retard amount Art is preferably such that the driver cannot feel that the ignition timing of the drive target has been retarded.

  When the torque value Trq in the cylinder 12 corresponding to the update target is smaller than the previous driving time, the processing unit 52 is the difference between the current target ignition timing Atar and the previous temporary target ignition timing Atstj, and The retardation amount SAArt (= Art × (j−2): j ≧ 2) until driving is calculated as the second update amount Arev2. For example, when the torque value Trq becomes small at the temporary target ignition timing Atstj (j = 2) next to the initial ignition timing, the processing unit 52 calculates the retardation amount SArt = 0 as the second update amount Arev2. That is, the second update amount Arev2 is a delay amount with respect to the initial ignition timing, and is a delay amount until the ignition timing at which the torque value Trq, that is, the output of the engine 10 becomes highest in the ignition timing range in which the margin Amar is ensured. Amount. The processing unit 52 updates the correction amount Acom by storing a new correction amount Acom obtained by delaying the correction amount Acom by the second update amount Arev2 in a predetermined area of the storage unit 53.

With reference to FIG. 3, an example of the update process executed by the processing unit 52 will be described. This process is repeatedly executed after the engine 10 is started, and each value is reset at the end.
As shown in FIG. 3, the processing unit 52 determines whether or not the operation state of the engine 10 is a steady state after completion of warm-up (step S11). When the operating state of the engine 10 is not a steady state after completion of warm-up (step S11: NO), the processing unit 52 once ends a series of processes.

  On the other hand, when the operating state of the engine 10 is a steady state after completion of warm-up (step S11: YES), the processing unit 52 calculates the air-fuel ratio AF of each cylinder 12 (step S12), and the calculated air-fuel ratio. An update target is detected based on the AF (step S13).

  Next, when the update target is set as a drive target, the processing unit 52 drives the update target at the temporary target ignition timing Atsti (step S14). Then, the processing unit 52 determines whether knocking has occurred in the cylinder 12 corresponding to the update target (step S15).

  When knocking has not occurred (step S15: NO), the processing unit 52 proceeds to the process of step S14 again. On the other hand, when knocking has occurred (step S15: YES), the processing unit 52 calculates the first update amount Arev1 based on the advance amount SAad and the margin Amar (step S16). Then, the processing unit 52 updates the correction amount Acom based on the first update amount Arev1 (step S17).

  Next, the processing unit 52 determines whether or not the operating state of the engine 10 is a steady state (step S18). When the operating state of the engine 10 is not a steady state (step S18: NO), the processing unit 52 once ends the update process. On the other hand, when the operating state of the engine 10 is a steady state (step S18: YES), the processing unit 52 drives the update target at the temporary target ignition timing Atstj (step S19), and the torque of the cylinder 12 corresponding to the update target. The value Trq is calculated (step S20). Then, the processing unit 52 determines whether or not the torque value Trq acquired in Step S20 is smaller than the previous torque value Trq (Step S21).

  When the torque value Trq is equal to or greater than the previous torque value Trq (step S21: NO), the processing unit 52 proceeds to the process of step S18 again. On the other hand, when the torque value Trq is smaller than the previous torque value Trq (step S21: YES), the processing unit 52 calculates the second update amount Arev2, which is the retardation amount SArt until the previous drive (step S22). ). Then, the processing unit 52 updates the correction amount Acom based on the second update amount Arev2 (step S23), and ends the update process once.

  Referring to FIG. 4, the operation of the ignition timing control device and the control method will be described taking the case where the ignition timing to be updated is under the following conditions shown in FIG. 4 as an example.

The target ignition timing Atar is the MBT (Minimum Spark Advance for Best Torque) ignition timing.
The actual ignition timing Aact, which is the actual ignition timing, is an advance timing side with respect to the target ignition timing Atar, and the margin for the knock ignition timing Aknk is smaller than the margin Amar.

  In the above case, in the update of the correction amount Acom related to knocking, the update target is driven at the temporary target ignition timing Atsti where the ignition timing gradually advances, but the starting point of the temporary target ignition timing Atsti is not the target ignition timing Atar. Actually, it is the actual ignition timing Aact. When the temporary target ignition timing Atsti reaches the knock ignition timing Aknk, the advance amount SAad until the temporary target ignition timing Atsti reaches the knock ignition timing Aknk is smaller than the margin Amar by the first update amount Arev1. Becomes clear. This margin Amar is a margin according to the driving state when knocking is detected. Therefore, by delaying the current correction amount Acom by the first update amount Arev1, the target ignition timing Atar is set to the first ignition timing A1 retarded by the margin Amar from the knock ignition timing Aknk.

  In the next update of the correction amount Acom related to the output of the engine 10, the update target is driven at the temporary target ignition timing Atstj where the ignition timing is gradually retarded. At this time, the starting point of the temporary target ignition timing Atstj is the first ignition timing A1. When the temporary target ignition timing Atstj reaches the MBT ignition timing where the torque value Trq is the highest in the ignition timing range in which the margin Amar is ensured, the torque value Trq decreases at the next temporary target ignition timing Atstj. By such a decrease in the torque value Trq, it is found that the immediately preceding temporary target ignition timing Atstj is the ignition timing with the highest torque value Trq. Therefore, the target ignition timing Atar is set to the optimum ignition timing by retarding the correction amount Acom by the retard amount SAArt until the ignition timing at which the highest torque value Trq is obtained, that is, the second update amount Arev2. The

According to the ignition timing control device and control method, the following effects can be obtained.
(1) Since the margin Amar is selected according to the operation state at the time of knock detection, the shortage of the margin Amar with respect to the knock ignition timing Aknk is suppressed, and as a result, the engine 10 is less likely to be knocked.

  (2) The update target is detected when the operating state of the engine 10 is a steady state. In the steady state, each spark plug 13 is driven under substantially the same conditions. Therefore, the spark plug 13 for which the correction amount Acom is to be updated is detected with high accuracy.

(3) Since the difference in ignition timing between the different spark plugs 13 is reflected in the air-fuel ratio AF, the update target can be detected based on the air-fuel ratio AF.
(4) By updating the correction amount Acom related to the output of the engine 10 after the correction amount Acom related to knocking is updated, the output in the cylinder 12 corresponding to the update target is increased while ensuring the margin Amar for knocking. . As a result, it is possible to improve fuel consumption and exhaust gas purification performance.

In addition, the said embodiment can also be updated and implemented suitably as follows.
The update of the correction amount Acom performed in the update process may be only the update of the correction amount Acom related to knocking. Even if it is such a structure, the effect described in said (1)-(3) is acquired.

  The output for each cylinder 12 is not limited to the torque value Trq, and may be calculated based on, for example, the angular acceleration of the crankshaft 10a based on the crank angle CA. Further, for example, the calculation may be performed based on a detection value of an ion sensor that detects an ion current based on ions generated by combustion in the cylinder 12.

The detection of the update target based on the air-fuel ratio AF may be performed as follows.
The processing unit 52 calculates an average value AFave of the air-fuel ratio AF of all the cylinders 12 from the calculation result of the air-fuel ratio AF, and calculates a deviation ΔAF between the calculated average value AFave and the air-fuel ratio AF of the cylinder 12 for each cylinder 12. To do. The processing unit 52 determines whether or not the absolute value of the deviation ΔAF is an abnormal value by setting a value larger than the threshold value ΔAFth determined that the ignition timing is different from that of the other spark plugs 13 as an abnormal value. When there is a spark plug 13 whose absolute value of the deviation ΔAF is an abnormal value, the processing unit 52 may detect the spark plug 13 as an update target. Further, the spark plug 13 having the largest absolute value of the deviation ΔAF may be detected as an update target. According to such a configuration, it is possible to detect the spark plug 13 having a different ignition timing from the other spark plugs 13 with high accuracy.

The detection of the update target is not limited to detection based on the air-fuel ratio AF, and may be performed based on the output of each cylinder 12 in a steady state, for example.
The detection of the update target is not limited to when the operation state of the engine 10 is in a steady state, and may be performed, for example, when the operation state of the engine 10 is in a transient state or an idling state.

  The control device 50 updated the correction amount Acom to be updated detected from among the plurality of spark plugs 13. Not limited to this, the control device 50 determines for each spark plug 13 whether or not a condition for updating the correction amount Acom is satisfied, and sets the correction amount Acom of the spark plug 13 that satisfies the condition separately. It may be updated. As a condition at this time, for example, whether or not the difference between the intake air-fuel ratio based on the intake air amount and the fuel injection amount and the air-fuel ratio AF based on the detected value of the air-fuel ratio sensor 36 exceeds a threshold value. Can be mentioned. Further, for example, whether or not the deviation degree between the required torque and the torque value Trq exceeds a threshold value can be mentioned.

  The control device 50 can also be applied to an SPI (Single Point Injection) type engine that supplies fuel to each cylinder 12 with one injector. The control device 50 can also be applied to an in-cylinder direct injection engine.

  The control device 50 may retard the correction amount Acom by the first update amount Arev1 when the margin Amar is larger than the advance amount SAad. Therefore, when the margin Amar is smaller than the advance amount SAad, the correction amount Acom need not be updated.

  Knocking detection includes knock information from the knock sensor 39, combustion pressure Pc, change in angular acceleration of the crankshaft 10a based on the crank angle CA, and detection values of an ion sensor that detects ion current in the cylinder 12, May be performed based on at least one of the following.

  DESCRIPTION OF SYMBOLS 10 ... Engine, 10a ... Crankshaft, 11 ... Cylinder block, 12 ... Cylinder, 13 ... Spark plug, 14 ... Intake manifold, 15 ... Exhaust manifold, 16 ... Intake passage, 17 ... Turbocharger, 18 ... Compressor, 19 ... Intercooler , 20 ... throttle valve, 21 ... surge tank, 25 ... exhaust passage, 26 ... turbine, 30 ... intake air amount sensor, 31 ... intake air pressure sensor, 32 ... intake air temperature sensor, 34 ... crank angle sensor, 35 ... cam angle sensor , 36 ... Air-fuel ratio sensor, 37 ... Cooling water temperature sensor, 38 ... Accelerator opening sensor, 39 ... Knock sensor, 40 ... Combustion pressure sensor, 41 ... Accelerator pedal, 50 ... Control device, 51 ... Acquisition unit, 52 ... Processing unit 53 ... Storage unit 55 ... Ignition map 56 Correction amount of data, 57 ... margin map.

Claims (3)

A knocking detection unit for detecting knocking separately for each of a plurality of cylinders constituting the engine;
An ignition map in which a base ignition timing, which is an ignition timing according to the operating state of the engine, is defined, and a margin from the ignition timing at which the knocking is detected is defined as a value according to the operating state at which the knocking is detected. A storage unit for storing the margin map being processed,
A ignition timing of the ignition plug provided for each of said cylinders an ignition timing control unit for controlling the individually, the said base ignition timing, the target ignition timing is the ignition timing based on the correction amount for the base ignition timing and a said ignition timing control unit for controlling the ignition timing of the ignition plug,
A correction amount storage unit that stores the correction amount for each of the plurality of spark plugs;
An update target detection unit that detects an update target that is a specific spark plug that updates the correction amount among the plurality of spark plugs;
An air-fuel ratio calculation unit that calculates the air-fuel ratio of each of a plurality of cylinders of the engine based on a detection value of an air-fuel ratio sensor provided in the exhaust passage of the engine,
The ignition timing control unit
When the update target detection unit detects the update target, the update target ignition timing is set each time the update target is set as a drive target until the knock detection unit detects knocking of a cylinder corresponding to the update target. Advancing by a predetermined amount from the target ignition timing to obtain an advance amount until knocking is detected in the cylinder corresponding to the update target, and the knocking detection unit performs knocking in the cylinder corresponding to the update target. Tokushi collected the margin in accordance with the operating condition by applying the operating state when it encounters the margin map,
When margin in the acquired is greater than the advance amount with the acquired, is the difference between the correction amount the acquired margin and the obtained advance amount to the correction amount of the update object storage unit stores to update to the direction in which the amount corresponding to the ignition timing is retarded in the first update amount,
The update target detection unit
Calculates the average value of air-fuel ratio for all cylinders when the engine is in a steady state, and supports cylinders whose absolute value of the deviation between the calculated average value and the air-fuel ratio of each cylinder is greater than or equal to a threshold value An ignition timing control device that detects a spark plug to be updated as the update target . It further includes an output calculation unit that calculates the output for each cylinder,
The ignition timing control unit
When the correction amount of the update target stored in the correction amount storage unit is updated by the amount of the first update amount , the update target is set as a drive target on the condition that the operating state of the engine is in a steady state. Each time setting is performed, the ignition timing to be updated is retarded by a predetermined amount from the target ignition timing based on the updated correction amount, and the output of the cylinder corresponding to the update target is increased each time the update target is driven. taken Tokushi,
When the output acquired with the latest drive to be updated is smaller than the output acquired with the drive immediately before the latest drive to be updated, the correction amount storage unit stores the output. updated correction amount the target a retard amount for the ignition timing by the amount of the second update amount is retarded amount at the time of driving the front the one ignition timing to update in a direction to retard claim 2. The ignition timing control device according to 1. An ignition timing control method for controlling an ignition timing of a spark plug to a target ignition timing that is an ignition timing based on a base ignition timing that is an ignition timing according to an operating state of an engine and a correction amount for the base ignition timing,
The control device for controlling the ignition timing is:
The ignition timing of spark plugs provided for each of a plurality of cylinders constituting the engine is controlled separately,
A storage unit for storing a margin map in which a margin from the ignition timing at which knocking is detected is defined as a value corresponding to the operation state at which knocking is detected ;
A correction amount storage unit that stores the correction amount separately for each of the plurality of spark plugs,
When the operating state of the engine is in a steady state, an average value of air-fuel ratios for all cylinders is calculated based on a detection value of an air-fuel ratio sensor provided in the exhaust passage of the engine, and the calculated average value and cylinder Detecting a specific spark plug corresponding to a cylinder whose absolute value of the deviation from the air-fuel ratio for each is equal to or greater than a threshold,
Each time the update target is set as the drive target, the advance timing until the knock timing of the cylinder corresponding to the update target is detected by advancing the ignition timing of the update target by a predetermined amount from the target ignition timing. acquires, preparative margin the knocking corresponding to the operating condition by applying the operating state to the margin map when the detected Tokushi,
When margin in the acquired is greater than the advance amount with the acquired, is the difference between the correction amount the acquired margin and the obtained advance amount to the correction amount of the update object storage unit stores the method of ignition timing to update in the direction of an amount corresponding ignition timing is retarded in the first update amount.