JP2018091168A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine control device capable of controlling an engine rotation number to a proper rotation number even in the state in which the friction is lowered with use, thereby at an early stage to hold a condition under which an ISC learning control is performed.SOLUTION: In the case where an ISC learning value is not updated (YES at Step S1), after it was reset at an initial learning value, and in the case where an engine rotation number is at or higher than a predetermined engine rotation number which is higher than the target idle speed (YES at Step S3), a suppression control (at Steps S4 and S5) for correcting the initial learning value to reduce the initial learning value thereby to suppress the engine rotation number is started before an ISC leaning control (an allowance at Step 7).SELECTED DRAWING: Figure 2

Description

  The present invention relates to a control device for an internal combustion engine.

  As a conventional control device for an internal combustion engine, one described in Patent Document 1 is known. The control apparatus for an internal combustion engine described in Patent Document 1 includes an ISC control that adjusts an engine control amount so that an actual engine rotation speed during idle operation of the internal combustion engine coincides with a target rotation speed, an opening degree of a throttle valve, And throttle learning control for learning the relationship with the amount of intake air passing through the throttle valve.

  The internal combustion engine controller temporarily controls engine friction learning to learn friction acting on the engine output shaft, and temporarily injects fuel into the internal combustion engine when the engine rotational speed exceeds a predetermined speed. And over-rotation prevention control for executing a fuel cut to be stopped.

  In addition, the control device for an internal combustion engine described in Patent Document 1 resets the learning value of the throttle learning control to the initial value when the fuel cut is executed a plurality of times during the execution of the ISC control. When the execution is repeated, the learning value of the engine friction learning control is reset to the initial value.

Japanese Patent Laying-Open No. 2015-59528

  However, in the control device for an internal combustion engine described in Patent Document 1, the initial value of the learning value when reset is performed prevents the engine stall in consideration of the friction of each part in an unused state. This is determined with priority, and is not set in consideration of the deterioration over time associated with the use of the internal combustion engine. That is, in the internal combustion engine, the friction of each part becomes smaller due to the smoothing of the friction surface and the lowering of the viscosity of the lubricating oil as the production is started.

  For this reason, in the control device for an internal combustion engine described in Patent Document 1, when the learning value is reset to the initial value in a state where the friction is reduced, the state where the engine speed is large continues. Further, since the state where the engine speed is high continues, it takes a long time to converge to an appropriate target idle speed.

  Therefore, the present invention provides an internal combustion engine that can control the engine speed to an appropriate speed even when the friction decreases with use, and can quickly establish the conditions for performing ISC learning control. The object is to provide a control device.

  An aspect of the invention of a control device for an internal combustion engine that solves the above problem includes a control unit that controls the engine speed of the internal combustion engine, and the control unit matches the engine speed during idling with a target idle speed. A control device for an internal combustion engine that executes ISC learning control that stores the throttle opening or the air flow rate correlated therewith as an ISC learning value. If the ISC learning value has not been updated since it was reset to the initial learning value, and the engine speed is equal to or greater than a predetermined engine speed that is greater than the target idle speed, the initial learning value is corrected to decrease. Then, the suppression control for suppressing the engine speed is started prior to the ISC learning control.

  As described above, according to the present invention, even when the friction decreases with use, the engine speed can be controlled to an appropriate speed, and the conditions for performing ISC learning control can be established early. .

FIG. 1 is a configuration diagram of a vehicle equipped with an internal combustion engine control apparatus according to an embodiment of the present invention. FIG. 2 is a flowchart for explaining the operation of the control device for the internal combustion engine according to the embodiment of the present invention. FIG. 3 is a diagram showing a correction coefficient calculation map of the control device for the internal combustion engine according to one embodiment of the present invention. FIG. 4 is a timing chart for explaining the operation of the control apparatus for an internal combustion engine according to one embodiment of the present invention. FIG. 5 is a diagram showing the throttle opening in each state according to the operation of the control apparatus for an internal combustion engine according to one embodiment of the present invention.

  An internal combustion engine control apparatus according to an embodiment of the present invention includes a control unit that controls an engine speed of an internal combustion engine, and the control unit matches an engine speed during idling with a target idle speed. A control device for an internal combustion engine that performs ISC learning control that sets a throttle opening and stores the set throttle opening or an air flow rate correlated therewith as an ISC learning value. If the engine speed has not been updated since it was reset to the initial learning value, and the engine speed is equal to or higher than the predetermined engine speed, which is greater than the target idle speed, the initial learning value is corrected to reduce the engine speed. Control is started prior to ISC learning control. As a result, the control apparatus for an internal combustion engine according to an embodiment of the present invention can control the engine speed to an appropriate speed even when the friction decreases with use, and the ISC learning control is performed. Can be established early.

  Hereinafter, an internal combustion engine control apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.

  In FIG. 1, a vehicle 1 equipped with an internal combustion engine control device according to an embodiment of the present invention includes an internal combustion engine 2 and an ECU (Electronic Control Unit) 3 as a control unit.

  The internal combustion engine 2 is configured by a four-cycle engine that performs a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke while the piston reciprocates twice within the cylinder.

  The piston housed in each cylinder is connected to the crankshaft via a connecting rod. The connecting rod converts the reciprocating motion of the piston into the rotational motion of the crankshaft.

  Therefore, the internal combustion engine 2 drives the vehicle 1 by causing the piston to reciprocate by burning a mixture of fuel and air in the combustion chamber 25 in the cylinder and rotating the crankshaft via the connecting rod. A driving force is generated.

  An intake manifold 31 for introducing air into the combustion chamber 25 is provided at the intake port of the internal combustion engine 2. The intake manifold 31 is connected to an intake pipe 32 for sucking outside air. That is, the intake manifold 31 communicates the intake pipe 32 and the intake port of each cylinder.

  The upstream portion of the intake manifold 31 forms a surge tank that temporarily stores air. An intake pressure sensor 27 is provided upstream of the intake manifold 31. The intake pressure sensor 27 detects the pressure of the intake manifold 31, and transmits a detection signal to the ECU 3.

  The intake pipe 32 is provided with a throttle valve 33 for adjusting the intake air amount of the internal combustion engine 2. The throttle valve 33 is configured as an electronically controlled throttle valve, and adjusts the intake air amount of the internal combustion engine 2 by controlling the throttle opening in accordance with a command signal from the ECU 3.

  The throttle valve 33 is provided with a throttle opening sensor 28. The throttle opening sensor 28 detects the opening of the throttle valve 33 and transmits a detection signal to the ECU 3 as the throttle opening.

  When the direction in which fresh air is introduced into the intake pipe 32 is the intake direction, the air flow sensor 21 is provided upstream of the throttle valve 33 in the intake direction. The air flow sensor 21 detects the flow rate of air flowing into the internal combustion engine 2.

  The exhaust port of the internal combustion engine 2 is provided with an exhaust manifold 41 for discharging the exhaust gas generated by the combustion of the air-fuel mixture in the combustion chamber 25 to the outside of the vehicle. The exhaust manifold 41 is connected to the exhaust pipe 42. That is, the exhaust manifold 41 communicates the exhaust pipe 42 and the exhaust port of each cylinder.

  The exhaust pipe 42 is provided with a three-way catalyst 43, an air-fuel ratio sensor 44, and an oxygen sensor 45. The three-way catalyst 43 purifies exhaust gas discharged from the combustion chamber 25 of the internal combustion engine 2, that is, burnt gas.

  Here, when the direction in which the exhaust gas is discharged is the exhaust direction, the air-fuel ratio sensor 44 is provided upstream of the three-way catalyst 43 in the exhaust direction. The oxygen sensor 45 is provided downstream of the three-way catalyst 43 in the exhaust direction.

  The air-fuel ratio sensor 44 and the oxygen sensor 45 detect whether the air-fuel ratio is on the rich side or the lean side with respect to the stoichiometric air-fuel ratio by detecting the oxygen concentration contained in the exhaust gas. It transmits to ECU3.

  The oxygen sensor 45 is an oxygen sensor having an output characteristic in which the output suddenly changes between the rich side and the lean side with respect to the air / fuel ratio with reference to the stoichiometric air / fuel ratio. The air-fuel ratio sensor 44 is a sensor having linear output characteristics with respect to the oxygen concentration.

  The fuel tank 51 stores gasoline as fuel for the internal combustion engine 2 in a normal pressure state. The gasoline stored in the fuel tank 51 is pumped by the fuel pump 51a and injected into the intake port from the injector 24 provided in the intake port of each cylinder.

  The internal combustion engine 2 includes variable valve timing mechanisms 26 on the intake side and the exhaust side, respectively. By controlling the variable valve timing mechanism 26 by the ECU 3, the intake timing, the exhaust timing, and the valve overlap amount can be adjusted. It has become.

  The fuel tank 51 is connected to a canister 52 that adsorbs evaporated fuel. A purge pipe 53 is connected to the canister 52, and the intake manifold 31 is connected to the opposite end of the purge pipe 53 to which the canister 52 is connected. The evaporated fuel adsorbed in the canister 52 is introduced into the intake manifold 31 through the purge pipe 53 together with air as purge gas.

  The purge pipe 53 is provided with a purge valve 54. The purge valve 54 is controlled to be opened and closed by the ECU 3. The ECU 3 controls the amount of purge gas introduced into the intake manifold 31 by controlling the opening and closing of the purge valve 54.

  The ECU 3 includes a computer unit that includes a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), a flash memory, an input port, and an output port.

  A program for causing the computer unit to function as the ECU 3 is stored in the ROM of the ECU 3 together with various control constants and various maps. That is, the computer unit functions as the ECU 3 when the CPU executes a program stored in the ROM.

  In addition to the airflow sensor 21, air-fuel ratio sensor 44, and oxygen sensor 45 described above, various sensors such as an accelerator opening sensor 22, an idle switch 29, and a crank angle sensor 23 are connected to the input port of the ECU 3.

  The accelerator opening sensor 22 detects the accelerator opening representing the operation amount of the accelerator pedal 22A, and transmits a detection signal to the ECU 3. The idle switch 29 transmits an ON signal to the ECU 3 when the accelerator pedal 22A is not depressed.

  The crank angle sensor 23 detects the rotation angle of the crankshaft of the internal combustion engine 2. The ECU 3 calculates the engine speed (engine speed) of the internal combustion engine 2 based on the detection result input from the crank angle sensor 23.

  Further, the ECU 3 calculates the amount of intake air per unit time (intake air amount) based on a signal from the air flow sensor 21. On the other hand, various devices such as the injector 24, the throttle valve 33, and the purge valve 54 are connected to the output port of the ECU 3.

  The ECU 3 sets the throttle opening so that the engine speed during idling of the internal combustion engine 2 matches the target idle speed. Then, the ECU 3 executes ISC learning control for storing and holding the set throttle opening as an ISC learning value. The ISC learning value may be an air flow rate correlated with the throttle opening instead of the throttle opening.

  The operation of the control apparatus for an internal combustion engine according to the present embodiment configured as described above will be described with reference to the flowchart of FIG.

  In FIG. 2, the ECU 3 determines whether or not the ISC learning value has been updated from the initial learning value (step S1). If it has not been updated, the ECU 3 determines whether or not the idle switch 29 is on ( Step S2). If it is determined in step S1 that the ISC learning value has been updated, or if it is determined in step S2 that the idle switch 29 is OFF, the ECU 3 ends the current operation.

  When it is determined in step S2 that the idle switch 29 is on, the ECU 3 determines whether or not the engine speed is equal to or higher than the predetermined engine speed (step S3). A reduction correction coefficient is determined (step S4), and the initial learning value is corrected to be reduced by multiplying the initial learning value by this reduction correction coefficient (step S5).

  The ECU 3 repeats steps S4 and S5 until the engine speed becomes less than the predetermined engine speed. Steps S4 and S5 constitute suppression control in the present invention. The suppression control for reducing the engine speed by reducing the initial learning value is continued until it is terminated in step S9 described later.

  When it is determined in step S3 that the engine speed is less than the predetermined engine speed, the ECU 3 repeats determination of whether or not a learning condition capable of starting ISC learning is satisfied (step S6). There are a plurality of learning conditions for each of a plurality of ISC learning values that differ depending on the vehicle state.

  For example, there are learning conditions corresponding to a cooling state with a low cooling water temperature and a warming-up completion state with a high cooling water temperature. Further, there are learning conditions for each operating region (engine speed, engine load, torque, etc.) of the internal combustion engine. Further, there is a learning condition for each gear stage or gear ratio of the transmission and whether or not an auxiliary machine such as an air conditioner is operated.

  If the learning condition is satisfied in step S6, the ECU 3 permits the first ISC learning control, that is, the first learning (step S7).

  Subsequent to step S7, the ECU 3 repeatedly determines whether or not ISC learning is completed (step S8). If ISC learning is completed, the ECU 3 finishes reducing the initial learning value (step S9), and the flowchart of FIG. Exit.

  In step S2, it is determined whether or not the idle switch 29 is on. If it is determined in step S3 that the engine speed is equal to or higher than the predetermined engine speed, this is determined by the driver. This is to distinguish whether it is due to a request (accelerator pedal operation) or not.

  Further, the predetermined engine speed used as the threshold value in step S3 is preferably set based on the vehicle state. For example, when the shift range is a travel range such as an R (reverse) range or a D (forward) range, the predetermined engine speed is set to a low value, and the shift range is a P (parking) range or an N (neutral) range. In the non-traveling range, the predetermined engine speed may be set to a high value.

  In step S3, instead of comparing the engine speed with a predetermined engine speed, the differential rotation between the actual engine speed and the target speed may be compared with a predetermined threshold value. However, in this case, if the target rotational speed changes suddenly due to, for example, switching of the operating state of the auxiliary machine, the differential rotation between the target rotational speed and the engine rotational speed also changes suddenly. For this reason, it is desirable to perform the control in consideration of being able to converge the engine speed without being affected by such a sudden change.

  FIG. 3 is a map that is referred to when calculating the weight loss correction coefficient in step S4 of FIG. This map is obtained in advance by experiments or the like and stored in the ECU 3.

  In this map, the correlation between the reduction correction coefficient and the engine speed is determined. In the region where the engine speed is less than the predetermined engine speed, the reduction correction coefficient is 1.0 (no reduction correction) and the engine speed is set. However, in a region where the engine speed is equal to or higher than the predetermined engine speed, the reduction correction coefficient is set to be smaller as the engine speed is higher. In other words, the correction amount for reducing the initial learning value is increased as the engine speed increases.

  2 will be described with reference to the timing chart of FIG. This timing chart shows a state change after the internal combustion engine 2 is started in a state where the ISC learning value is not updated after being reset to the initial learning value.

  More specifically, this timing chart shows changes over time in the engine speed, the suppression control flag, and the learning permission flag. Here, the suppression control flag is established when it is determined in step S3 in the flowchart of FIG. 2 that the engine speed is equal to or higher than the predetermined engine speed. The learning permission flag is set when it is determined that the learning condition is satisfied in step S6 of the flowchart of FIG. 2 and the first learning is permitted in step S7.

  At time t1, the engine speed increases as indicated by the solid line due to the input of a disturbance such as a load on the auxiliary machine. Thereafter, at time t2, the suppression control flag is established because the engine speed has risen above the predetermined engine speed, and the suppression control is started.

  In this suppression control, the engine speed is suppressed by a decrease correction for the ISC learning value. As a result, the engine speed converges to the target engine speed, and the learning permission flag is established at time t3. In this timing chart, the case where no disturbance such as the load of the auxiliary machine is inputted and the engine speed does not increase greatly is indicated by a broken line.

  FIG. 5 shows an example of the throttle opening in each state related to the ISC learning value. The vertical axis in FIG. 5 is the throttle opening, and the horizontal axis is the state after learning of the ISC learning value from the left, the state after resetting the ISC learning value to the initial learning value (before learning), and after executing the suppression control. It is a state.

  Each state shows a case where the air conditioner is operating and the shift range is the D range. The vertical axis may be an air flow rate correlated with the throttle opening instead of the throttle opening.

  In FIG. 5, after learning the ISC learning value, the learning value, the correction amount for the A / C correction due to the operation of the air conditioner, and the correction amount for the D range correction due to the shift range being the D range. Is the throttle opening.

  After resetting to the initial learning value (before learning), the throttle opening is the sum of the initial learning value, the correction amount for A / C correction, and the correction amount for D range correction. After execution of the suppression control, the throttle opening is the sum of the initial learning value corrected for reduction, the correction amount for A / C correction, and the correction amount for D range correction.

  The initial learning value is larger than the idling engine speed that is excellent in fuel efficiency and quietness in order to prevent a stall in a high friction state when the internal combustion engine 2 is first started after being produced at the factory. . For this reason, the ISC learning value obtained by learning is smaller than the initial learning value.

  Here, when the ISC learning value is reset to the initial learning value, the first learning is performed on the condition that the engine speed is stable. Therefore, the initial learning is not performed and the initial learning value is not updated before the convergence of the engine speed.

  Therefore, in this embodiment, when the engine speed does not converge when the ISC learning value is not updated after being reset to the initial learning value, the initial learning value is multiplied by a reduction correction coefficient to reduce the amount of correction. The engine speed is converged by performing control using the obtained initial learning value, so that the initial learning can be performed at an early stage.

  Thus, in this embodiment, the ECU 3 sets the throttle opening so that the engine speed during idling matches the target idle speed, and sets the throttle opening or the air flow rate correlated therewith to the ISC. ISC learning control stored as a learning value is executed.

  When the ISC learning value has not been updated since the ISC learning value was reset to the initial learning value, and the engine speed is equal to or higher than the predetermined engine speed that is greater than the target idle speed, the ECU 3 reduces the initial learning value by a decrease. Then, the suppression control for suppressing the engine speed is started prior to the ISC learning control.

  According to the present embodiment, since the engine speed is suppressed by reducing the initial learning value to reduce the engine speed, the engine speed can be appropriately suppressed without being influenced by the driving state of the auxiliary machine. That is, since the engine speed is not suppressed by an excessive correction amount that takes into account the load of the auxiliary machine, the engine speed is controlled to an appropriate speed without causing the internal combustion engine 2 to stall due to the excessive correction amount. it can. Moreover, the conditions under which ISC learning control is performed can be established early by suppressing the engine speed.

  As a result, the engine speed can be controlled to an appropriate speed even when the friction is reduced with use, and the conditions under which ISC learning control is performed can be established early.

  In this embodiment, the ECU 3 increases the correction amount for reducing the initial learning value as the engine speed increases.

  According to this embodiment, as the engine speed increases, the initial learning value is corrected to decrease with a large correction amount, so that the engine speed can be quickly converged.

  In the present embodiment, the ECU 3 ends the suppression control when a predetermined correction end condition is satisfied. The correction end condition is either that the engine speed has converged to the target idle speed or that the learning value has been updated.

  According to this embodiment, the suppression control is continued until either the engine speed has converged to the target idle speed or the learning value has been updated, so that the ISC learning control is performed. Can be established early, and the ISC learning value can be reliably updated by the ISC learning control.

  In this embodiment, the ECU 3 sets a predetermined engine speed based on the vehicle state.

  According to the present embodiment, conditions for performing ISC learning control can be established early for all ISC learning values for each vehicle state.

  While embodiments of the invention have been disclosed, it will be apparent to those skilled in the art that changes may be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

2 Internal combustion engine 3 ECU (control unit)

Claims (4)

A control unit for controlling the engine speed of the internal combustion engine;
The controller is
The throttle opening is set so that the engine speed during idling matches the target idle speed, and the set throttle opening or the air flow rate correlated therewith is stored as an ISC learning value. A control device for an internal combustion engine,
The controller is
When the ISC learning value has not been updated since it was reset to the initial learning value, and the engine speed is equal to or higher than a predetermined engine speed greater than the target idle speed,
A control apparatus for an internal combustion engine, wherein suppression control for reducing the engine speed by reducing the initial learning value is started prior to the ISC learning control. The controller is
2. The control apparatus for an internal combustion engine according to claim 1, wherein the correction amount for reducing the initial learning value is increased as the engine speed increases. The controller is
When the predetermined correction end condition is satisfied, the suppression control is ended,
3. The correction end condition is any one of the convergence of the engine speed to the target idle speed or the update of the learning value. The control apparatus of the internal combustion engine described in 1. The controller is
The control device for an internal combustion engine according to any one of claims 1 to 3, wherein the predetermined engine speed is set based on a vehicle state.

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