JP2019070374A - Control device for internal combustion engine - Google Patents

Abstract

To provide a control device for an internal combustion engine capable of controlling ignition timing so as to eliminate the knocking in an early stage while securing torque.SOLUTION: An ECU 10 is applied to an internal combustion engine 90 having a plurality of cylinders. The ECU 10 includes a knocking detecting section 11 which can detect occurrence of knocking in cylinders for each of the cylinders. The ECU 10 includes an ignition timing control section 12 for executing all-cylinder control for controlling the ignition timing of all of the cylinders and each-cylinder control for controlling the ignition timing of the cylinders for each of the cylinders, as ignition timing control for controlling the ignition timing on the basis of the existence/absence of the occurrence of the knocking detected by the knocking detecting section 11. Further, the ECU 10 includes a shift section 13 for allowing the ignition timing control section 12 to execute the all-cylinder control during a predetermined period after starting of the internal combustion engine 90 and shifting the ignition timing control from the all-cylinder control to the each-cylinder control after execution of the all-cylinder control.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device for an internal combustion engine that controls ignition timing.

Patent Document 1 discloses a control device that performs ignition timing control for detecting the occurrence of knocking and retarding the ignition timing.
With regard to a control device for an internal combustion engine that executes such ignition timing control, as disclosed in Patent Document 1, all cylinders that retard the ignition timing for all cylinders based on the occurrence of knocking in any of the cylinders Control and cylinder-by-cylinder control that detects the occurrence of knocking in each cylinder and retards the ignition timing for each cylinder are known.

JP 2007-327346 A

  In the all-cylinder control, the ignition timing is retarded even for cylinders in which knocking has not occurred, so there may be a shortage of torque due to a reduction in torque accompanying the retardation of the ignition timing. On the other hand, in the cylinder-by-cylinder control, there is a possibility that knocking may occur in each cylinder until the ignition timing is retarded in each cylinder. For this reason, in a situation where knocking easily occurs, knocking in a plurality of cylinders continues in comparison with full cylinder control in which the ignition timing of all cylinders is retarded based on the occurrence of knocking in one of the cylinders. Problem that it is easy to occur.

  Under such circumstances, it has been conventionally proposed to use all-cylinder control and cylinder-by-cylinder control depending on the operating state of the internal combustion engine. However, the control mode to control to eliminate knocking early while securing torque There was room.

  A control device for an internal combustion engine to solve the above problems is applied to an internal combustion engine having a plurality of cylinders, and a knocking detection unit capable of detecting the presence or absence of knocking in the plurality of cylinders for each cylinder; As ignition timing control for controlling the ignition timing based on the presence or absence of occurrence of knocking detected by the ignition timing, the ignition timings of all cylinders of the plurality of cylinders based on the presence or absence of occurrence of knocking in any of the plurality of cylinders. A control device for an internal combustion engine, comprising: an all-cylinder control to be controlled; and an ignition timing control unit that controls cylinder-by-cylinder control of ignition timing of each cylinder based on presence or absence of knocking for each cylinder. And causes the ignition timing control unit to execute the all-cylinder control in a specified period after the start of the internal combustion engine, and after performing the all-cylinder control, That the ignition timing control from the full cylinder control includes a transition section to shift to the cylinder controller as its gist.

  If cylinder-by-cylinder control is performed when the internal combustion engine is started, knocking may occur continuously. Furthermore, there is a possibility that the state in which the torque is lowered may be prolonged by retarding the ignition timing with the occurrence of knocking for each cylinder. In addition, if all-cylinder control is continued from the start, torque reduction is forced each time knocking occurs in any of the cylinders. According to the above configuration, it is possible to contribute to the early elimination of knocking while suppressing the decrease in torque caused by the retardation of the ignition timing for suppressing the knocking.

FIG. 2 is a relationship diagram showing an ECU that is an embodiment of a control device for an internal combustion engine and an internal combustion engine that is a control target of the ECU. The flowchart of the transfer determination processing which the transfer part of the same ECU performs. The flowchart which shows the flow of the fundamental processing in ignition timing control which the ignition timing control part of the same ECU performs. The flowchart which shows the flow of the learning process in ignition timing control. Explanatory drawing explaining the setting aspect of the ignition timing by ignition timing control.

Hereinafter, an electronic control unit (hereinafter referred to as "ECU 10"), which is an embodiment of a control device for an internal combustion engine, will be described with reference to FIGS.
An internal combustion engine 90 controlled by the ECU 10 shown in FIG. 1 includes a plurality of cylinders in a cylinder block. An intake passage 94 is connected to the combustion chamber 91 of each cylinder. A throttle valve 95 is provided in the intake passage 94. Further, a fuel injection valve 96 is provided in the intake passage 94. In the internal combustion engine 90, a mixture of air and fuel is introduced into the combustion chamber 91 through the intake passage 94.

  In the combustion chamber 91, a spark plug 92 is provided. The combustion chamber 91 is provided with a piston 93 capable of reciprocating. The internal combustion engine 90 includes, as an output shaft, a crankshaft 98 that rotates in conjunction with the reciprocation of the piston 93. Connected to the combustion chamber 91 is an exhaust passage 97 for discharging the air-fuel mixture after combustion from the combustion chamber 91.

  The internal combustion engine 90 is provided with various sensors such as an air flow meter 81, a crank position sensor 82, a knock sensor 83, and a water temperature sensor 84. The air flow meter 81 detects an intake air amount Ga which is an amount of air taken into the combustion chamber 91 through the intake passage 94. The crank position sensor 82 outputs a signal corresponding to a change of a crank angle which is a rotation angle of the crankshaft 98, a crank angle used for calculation of an engine rotation speed, and the like. The knock sensor 83 is provided in the cylinder block, and outputs a signal corresponding to the magnitude of knocking generated in the cylinder. The water temperature sensor 84 detects the water temperature THW as the temperature of the cooling water circulating in the water jacket of the internal combustion engine 90. Signals from various sensors are input to the ECU 10.

The ECU 10 includes a knocking detection unit 11, an ignition timing control unit 12, and a transition unit 13 as functional units.
The knocking detection unit 11 detects the occurrence of knocking based on the signal input from the knock sensor 83. The knocking detection unit 11 can also determine which of the plurality of cylinders the knocking has occurred.

  The ignition timing control unit 12 executes ignition timing control that retards or advances the ignition timing. The ignition timing control advances the ignition timing gradually when the occurrence of knocking is not detected, and retards the ignition timing gradually when the occurrence of knocking is detected, until just before the occurrence limit of knocking. It is performed to advance the ignition timing. In the ignition timing control, a learning process for learning an ignition timing at which knocking occurs is limited.

  The ignition timing control performed by the ignition timing control unit 12 includes all-cylinder control that controls the ignition timing for all cylinders of a plurality of cylinders, and cylinder-specific control that controls the ignition timing for each cylinder for each cylinder. . The ignition timing control unit 12 executes all-cylinder control or cylinder-by-cylinder control based on an instruction from a transition unit 13 described later.

  The transition unit 13 instructs the ignition timing control unit 12 to execute the all-cylinder control after the internal combustion engine 90 is started. Further, the transition unit 13 executes transition determination processing of ignition timing control, and instructs the ignition timing control unit 12 to shift the ignition timing control from all-cylinder control to cylinder-by-cylinder control based on the processing result.

  With reference to FIG. 2, the processing routine of the migration determination processing executed by the migration unit 13 will be described. The present process is repeatedly performed at predetermined time intervals until the ignition timing control switches from the all-cylinder control to the cylinder-by-cylinder control after the internal combustion engine 90 is started.

  When the execution of the processing routine is started, first, in step S101, the transition unit 13 determines whether the condition A is satisfied. If the condition A is not satisfied (step S101: NO), this processing routine is temporarily ended. On the other hand, when the condition A is satisfied (step S101: YES), the process proceeds to step S102.

Condition A in step S101 is determined to be satisfied when at least one of the following conditions (i) and (ii) is satisfied.
(A) The elapsed time from the completion of the warm-up of the internal combustion engine 90 is equal to or longer than the specified time.
(Ii) The integrated value of the intake air amount Ga after the start of the start of the internal combustion engine 90 is equal to or greater than a specified value.

  Whether or not the warm-up of the internal combustion engine 90 is completed is determined based on the water temperature THW. Further, as the prescribed time and the prescribed value, values for determining whether or not a prescribed period after the start of the start of the internal combustion engine 90 has elapsed are set.

  In step S102, the transition unit 13 determines whether the condition B is established. If the condition B is not satisfied (step S102: NO), this processing routine is temporarily ended. On the other hand, when the condition B is satisfied (step S102: YES), the process proceeds to step S103.

Condition B in step S102 is determined to be satisfied when at least one of the following conditions (c) and (d) is satisfied.
(C) In idle operation.
(D) Fuel cut is in progress.

  In step S103, the transition unit 13 instructs the ignition timing control unit 12 to end all-cylinder control and start execution of cylinder-by-cylinder control. By this, execution of cylinder-by-cylinder control is started. Thereafter, the processing routine is ended.

In the transition determination process executed by the transition unit 13, transition conditions of ignition timing control are configured by the conditions A and B described above.
Next, with reference to FIG. 3, the flow of the basic processing of ignition timing control will be described. This series of processing is executed by the ignition timing control unit 12 and the knocking detection unit 11. Further, this series of processing is repeatedly performed at predetermined control cycles while the internal combustion engine 90 is in operation. The ignition timing is represented by a crank angle to the advance side with reference to the compression top dead center. That is, the value indicating the ignition timing becomes larger as the ignition timing is more advanced than the compression top dead center.

  When execution of this series of processing is started, first, in step S201, the ignition timing control unit 12 calculates a basic ignition timing ABSE and a limit retarded ignition timing AKMF based on the engine rotation speed and the engine load. The engine load is obtained from the intake air amount Ga detected by the air flow meter 81 or the like.

  The basic ignition timing ABSE is either the optimal ignition timing at which the torque generation efficiency of the internal combustion engine 90 becomes maximum, or the knock limit ignition timing which is the advance angle limit of the ignition timing, whichever is the retarded timing. The knock limit ignition timing is a limit value on the retard side of the range of the ignition timing at which occurrence of knocking is confirmed. Further, the limit retarded ignition timing AKMF is an advance-side limit value of the ignition timing range in which it is confirmed that knocking does not occur even under conditions in which knocking tends to occur.

  From the point of improvement of the fuel consumption rate, it is advantageous to set the ignition timing (target ignition timing AOP) finally set to a timing as close as possible to the basic ignition timing ABSE. On the other hand, even if the target ignition timing AOP is set to a timing that is more retarded than the limit retarded ignition timing AKMF, it is meaningless in terms of suppression of knocking. Therefore, in the ignition timing control, the target ignition timing AOP is controlled within the range from the limit retarded ignition timing AKMF to the basic ignition timing ABSE.

After the basic ignition timing ABSE and the limit retarded ignition timing AKMF are calculated in step S201, the process proceeds to step S202.
In step S202, the ignition timing control unit 12 sets the difference between the basic ignition timing ABSE and the limit retarded ignition timing AKMF as the value of the limit retarded amount AKMAX. Thereafter, the process proceeds to step S203. The limit retardation amount AKMAX is an upper limit value of the retardation amount of the target ignition timing AOP with respect to the basic ignition timing ABSE in the ignition timing control.

  In step S203, based on the detection result of knock sensor 83, knocking detection unit 11 checks whether knocking has occurred. If it is confirmed that knocking has not occurred (step S203: NO), the process proceeds to step S204. In step S204, the ignition timing control unit 12 decreases the value of knock control amount AKCS. The reduction amount of knock control amount AKCS at this time is taken as a constant.

  On the other hand, when occurrence of knocking is confirmed in step S203 (step S203: YES), the process proceeds to step S205. In step S205, the ignition timing control unit 12 increases the value of knock control amount AKCS. The knock control amount AKCS is expressed by a crank angle, and is a value indicating that the larger the value is, the larger the amount by which the ignition timing is retarded. The initial value is “0”. The increase amount of knock control amount AKCS at this time is set in accordance with the detected knocking intensity and the occurrence frequency. Here, the amount of increase in knock control amount AKCS is increased as the magnitude of knocking increases or as the frequency of occurrence of knocking increases.

After updating the knock control amount AKCS in step S204 or step S205, the process proceeds to step S206.
In step S206, the ignition timing control unit 12 calculates an ignition timing retardation amount AKNK, which is a retardation amount of the ignition timing from the basic ignition timing ABSE. The calculation of the ignition timing retardation amount AKNK is performed by adding the knock control amount AKCS to the limit retardation amount AKMAX, and subtracting the knock learning value AGKNK (AKNK ← AKMAX + AKCS-AGKNK). Knock learning value AGKNK is a value that is represented by a crank angle, and indicates that the larger the value is, the larger the amount by which the ignition timing is advanced, and is a value set in a learning process described later.

  When the ignition timing retardation amount AKNK is calculated in step S206, the process proceeds to step S207. In step S207, the ignition timing control unit 12 sets a target ignition timing AOP. The setting of the target ignition timing AOP is performed by correcting the basic ignition timing ABSE to the retard side by an amount corresponding to the ignition timing retardation amount AKNK. Specifically, a difference obtained by subtracting the ignition timing retardation amount AKNK from the basic ignition timing ABSE is set as a target ignition timing AOP. (AOP ← ABSE-AKNK).

  Thus, when the target ignition timing AOP is set in step S207, this series of processing is temporarily ended. Then, the ignition timing control unit 12 controls the ignition plug 92 such that ignition is performed at the target ignition timing AOP set here.

  Next, with reference to FIG. 4, a processing routine of learning processing in ignition timing control will be described. This learning process follows the basic process of the ignition timing control described with reference to FIG. 3 and continues until the series of processes described with reference to FIG. It is executed by the control unit 12.

  When the processing routine is started, first, at step S301, it is determined by the ignition timing control unit 12 whether the gradual change value of the knock control amount AKCS is larger than a prescribed positive value "α". The gradual change value of knock control amount AKCS is a so-called smoothed value obtained by performing processing to make the increase / decrease speed of knock control amount AKCS slower. If it is determined in step S301 that the gradual change value of knock control amount AKCS is less than or equal to “α” (step S301: NO), the process proceeds to step S302.

  In step S302, the ignition timing control unit 12 determines whether the gradual change value of the knock control amount AKCS is smaller than “−α”. In step S302, when the gradual change value of knock control amount AKCS is smaller than “−α” (step S302: YES), the process proceeds to step S303.

  In step S303, the ignition timing control unit 12 increases the value of knock learning value AGKNK by a prescribed amount. In step S303, the value of knock learning value AGKNK is increased by a prescribed amount, and the value of knock control amount AKCS is similarly increased by a prescribed amount. Further, the initial value of knock learning value AGKNK is “0”, and the prescribed amount is a value smaller than “α”. Thus, when the value of knock learning value AGKNK is updated in step S303, the processing routine is temporarily ended.

  On the other hand, when the gradual change value of knock control amount AKCS is "-α" or more in step S302 (step S302: NO), ignition timing control unit 12 changes the value of knock learning value AGKNK and knock control amount AKCS. This processing routine is once ended without changing the value of. In this case, the gradual change value of knock control amount AKCS is equal to or greater than “−α” and equal to or smaller than “α”.

If it is determined in step S301 that the gradual change value of knock control amount AKCS is larger than “α” (step S301: YES), the process proceeds to step S304.
In step S304, the ignition timing control unit 12 decreases the value of knock learning value AGKNK by a prescribed amount. In step S304, the value of knock learning value AGKNK is decreased by a prescribed amount, and the value of knock control amount AKCS is similarly decreased by a prescribed amount. Further, the initial value of knock learning value AGKNK is “0”, and the prescribed amount is a value smaller than “α”. Thus, when the value of knock learning value AGKNK is updated in step S304, the present processing routine is temporarily ended.

  As shown in FIG. 5, according to the ignition timing control described with reference to FIGS. 3 and 4, the ignition timing retardation amount AKNK which is the retardation amount of the ignition timing from the basic ignition timing ABSE is The limit retardation amount AKMAX is corrected to decrease by the value of knock learning value AGKNK, and is set to an amount corrected to increase by the value of knock control amount AKCS. As described above, the value of knock control amount AKCS increases when occurrence of knocking is confirmed, and decreases when it is not confirmed. Therefore, the target ignition timing AOP, which is the ignition timing delayed from the basic ignition timing ABSE by the ignition timing retardation amount AKNK, is gradually advanced until the occurrence of knocking is confirmed, The value settles to the ignition timing advanced to a point just before the ignition timing at which knocking occurs. Further, the value of knock learning value AGKNK is updated through learning processing so as to decrease the absolute value of knock control amount AKCS as the absolute value of knock control amount AKCS increases.

  Although the value of knock control amount AKCS is reset to "0" when the ignition switch is turned "OFF", the value of knock learning value AGKNK is stored in ECU 10 even after the ignition switch is turned "OFF". It is held in the region and taken over to the ignition timing control at the time of the next engine operation.

The all-cylinder control and the cylinder-by-cylinder control are executed based on the basic processing flow of ignition timing control described with reference to FIGS. 3 and 4, but different processing is performed in the following points.
In the all-cylinder control, in step S203 of FIG. 3, it is determined by the knocking detection unit 11 whether knocking has occurred in any of the plurality of cylinders. The processing of step S204 and subsequent steps is executed based on the determination result, and the ignition timing retardation amount AKNK is set for all cylinders.

In the cylinder-by-cylinder control, a series of processing of the ignition timing control described using FIGS. 3 and 4 is performed for each cylinder for each cylinder.
Further, in the ignition timing control executed by the ECU 10, as shown in FIG. 5, the sum of the common learning value AGKNKCOM and the individual cylinder learning value AGKNKCYL (n) is used as the knock learning value AGKNK. Here, “n” is a positive integer and corresponds to the cylinder number of the internal combustion engine 90. In each cylinder, ignition timing control is performed using a cylinder-by-cylinder learning value AGKNKCYL (n) corresponding to each cylinder. The common learning value AGKNKCOM and the cylinder-by-cylinder learning value AGKNKCYL (n) are respectively stored in different sections of the storage area provided in the ECU 10.

  The common learning value AGKNKCOM is updated in the learning process of all-cylinder control. In the learning process of the all-cylinder control, the cylinder-by-cylinder learning value AGKNKCYL (n) is held at that value. That is, in the processes of steps S303 and S304 in the all-cylinder control, the knock learning value AGKNK is updated by holding the value of the cylinder-by-cylinder learning value AGKNKCYL (n) and updating the common learning value AGKNKCOM.

  On the other hand, the cylinder-by-cylinder learning value AGKNKCYL (n) is updated in the cylinder-by-cylinder control learning process. In the learning process of the cylinder-by-cylinder control, the common learning value AGKNKCOM is held at that value. That is, in the processing of steps S303 and S304 in the cylinder-by-cylinder control, the value of common learning value AGKNKCOM is held and the value of cylinder-by-cylinder learning value AGKNKCYL (n) is updated to update knock learning value AGKNK.

Thus, one of the learning values constituting knock learning value AGKNK is held without being affected by the learning process for the other learning value.
Next, the operation of the ECU 10 according to the present embodiment and the effects thereof will be described.

  According to the ECU 10, the period in which the all-cylinder control is performed as the ignition timing control is a defined period after the start of the internal combustion engine 90 is started, specifically, a period until the transition condition is satisfied. By this, it is possible to shorten the period in which the torque shortage may occur due to the torque decrease. That is, it is possible to contribute to the early elimination of knocking while suppressing the decrease in torque resulting from the retardation of the ignition timing for suppressing the knocking.

  Furthermore, the ECU 10 sets condition A as a transition condition for determining whether to shift the ignition timing control from the all-cylinder control to the cylinder-by-cylinder control. Thus, it can be determined whether or not a specified period has elapsed since the start of the start of the internal combustion engine 90. Further, by setting the condition B, it is executed only when the transition of the ignition timing control is in the idle operation or the fuel cut. Thus, it is possible to suppress the occurrence of torque fluctuation when shifting the ignition timing control.

  For example, when fuel is replenished, if the properties of the fuel in the fuel tank and the properties of the replenished fuel are different, learning of the common learning value AGKNKCOM in all-cylinder control allows fuel before and after refilling. The difference in the characteristics is reflected in the common learning value AGKNKCOM. After that, when shifting to cylinder-based control, the knock learning value AGKNK is the sum of the common learning value AGKNKCOM and the cylinder specific learning value AGKNKCYL (n), so the common learning value AGKNKCOM reflecting the difference in fuel properties is The calculation of the ignition timing retardation amount AKNK is performed using this. By this, it is possible to promptly reflect the difference in fuel properties in the cylinder-by-cylinder control without learning the difference in fuel properties again after the transition from the all-cylinder control to the cylinder-by-cylinder control.

  Further, if the storage area of the learning value is common to all-cylinder control and cylinder-by-cylinder control, the learning value is overwritten along with switching of the ignition timing control, and the learning value before transition is reset. It will In this respect, according to the ECU 10, the common learning value AGKNKCOM in the all-cylinder control at the previous execution is the same even when the all-cylinder control is executed again after the ignition timing control is shifted from the all-cylinder control to the cylinder-by-cylinder control. It is held. That is, ignition timing control can be performed using the common learning value AGKNKCOM in which learning is reflected.

In addition, the said embodiment can also be implemented with the following forms which changed this suitably.
The process flow described with reference to FIGS. 3 and 4 in the above embodiment is an example of the process of ignition timing control. The specific process flow of ignition timing control is not limited to this, and can be changed as appropriate.

  In the above embodiment, the conditions A and B are set as the transition conditions for shifting the ignition timing control from the all-cylinder control to the cylinder-by-cylinder control, but the transition conditions including the conditions A and B can be changed. For example, only condition A can be adopted as the transition condition. In addition, the condition A can be appropriately employed in place of the condition A, as long as the condition is set so as to determine that the specified period has elapsed since the start of the start of the internal combustion engine 90. For example, the actual time corresponding to the specified period may be derived by experiment or the like, and it may be determined that the transition condition is satisfied when the actual time has elapsed from the start of the start.

  In the above embodiment, although the control target of the ECU 10 is the internal combustion engine 90 shown in FIG. 1, the ECU 10 can be applied to any internal combustion engine having a plurality of cylinders.

  DESCRIPTION OF SYMBOLS 10 ... ECU, 11 ... knocking detection part, 12 ... Ignition timing control part, 13 ... Transition part, 81 ... Air flow meter, 82 ... Crank position sensor, 83 ... Knock sensor, 84 ... Water temperature sensor, 90 ... Internal combustion engine, 91 ... Combustion chamber, 92: spark plug, 93: piston, 94: intake passage, 95: throttle valve, 96: fuel injection valve, 97: exhaust passage, 98: crankshaft.

Claims (1)

Applied to internal combustion engines with multiple cylinders,
A knocking detection unit capable of detecting for each cylinder whether or not knocking has occurred in the plurality of cylinders;
As ignition timing control for controlling the ignition timing based on the occurrence of knocking detected by the knocking detection unit, all cylinders of the plurality of cylinders based on the presence or absence of knocking in any of the plurality of cylinders Internal combustion engine comprising: all-cylinder control for controlling the ignition timing of the engine; and an individual-cylinder control for controlling the ignition timing of each cylinder for each cylinder based on the presence or absence of knocking for each cylinder Control device of
In the specified period after the start of the internal combustion engine, the ignition timing control unit executes the all-cylinder control, and after the all-cylinder control is executed, the ignition timing control is controlled from the all-cylinder control to the individual cylinder control A control unit for an internal combustion engine, comprising: