JP2011043098A - Engine control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine control device to prevent the drive feeling from worsening by eliminating a delay in acceleration response due to a temporary torque shortage till attainment of the target valve timing when learning the lock position of a variable valve timing mechanism is finished by accelerator manipulation conducted by the driver. <P>SOLUTION: When the driver stamps in an accelerator pedal and learning the lock position is finished, the actual valve timing A is sensed and the target valve timing B is calculated (S2). If the time with the condition being ¾A-B¾>α, or ¾A-B¾≤α, has not reached set time, the ignition timing is corrected (S4), and if the time of condition ¾A-B¾≤α has elapsed for the set time, correcting the ignition timing is finished (S5). This allows eliminating the delay in acceleration response due to a temporary torque shortage until learning the lock position is finished and the target valve timing is attained, and it is possible to prevent the drive feeling from worsening. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an engine control device having a variable valve timing mechanism that adjusts a rotational phase between an engine crankshaft and a camshaft.

  In recent years, an engine equipped with a valve timing control system that adjusts the rotational phase between the crankshaft and the camshaft of the engine has been put into practical use. In such an engine with a variable valve timing mechanism, it depends on the engine operating state. The valve timing of at least one of the intake valve and the exhaust valve is continuously changed.

  Here, the variable valve timing mechanism generally employs a hydraulic drive type driven by hydraulic pressure, and includes a lock mechanism that mechanically locks at a predetermined reference position, and learns this reference position. This prevents a decrease in controllability due to individual variations in the variable timing mechanism and the influence of aging.

  For example, in Patent Document 1, the variable valve timing is mechanically locked (locked) to a reference position between the most advanced angle position and the most retarded angle position, so that the oil temperature after starting the engine is low, A technique for ensuring the intake air amount and facilitating starting of the internal combustion engine is disclosed.

  Further, Patent Document 2 prevents variations in the most retarded angle amount by learning the most retarded amount by mechanically locking the most retarded angle position to the reference position and mechanically locking to the most retarded position other than during idling. Techniques to do this are disclosed.

Japanese Patent Laid-Open No. 11-210424 JP 2000-328969 A

  By the way, if the driver depresses the accelerator pedal during the lock position learning, the lock position learning is finished and the control shifts to the target valve timing. However, after the lock is released, the cam angle phase reaches the target valve timing. In the meantime, the torque is temporarily insufficient, a response delay occurs with respect to the driver's accelerator depression, and the drive feeling may be deteriorated. In addition, even if the control to the target valve timing is started by depressing the driver's accelerator pedal before the lock position learning is finished and the lock is released or after the learning is finished, the valve timing is still When it is in the lock position, it is the control to the target valve timing after releasing the lock, or the control to the target valve timing from the lock position, so the same until the cam angle phase reaches the target valve timing However, there is a risk that the torque will be insufficient and drive feeling will deteriorate.

  The present invention has been made in view of the above circumstances. When the driver's accelerator operation finishes the lock position learning of the variable valve timing mechanism, or during the control transition to the target valve timing after the lock position learning ends, the driver performs the accelerator operation. It is an object of the present invention to provide an engine control device that can eliminate a delay in acceleration response due to a temporary shortage of torque until the target valve timing is reached, and prevent deterioration in drive feeling.

  In order to achieve the above object, an engine control apparatus according to the present invention provides a variable valve timing for adjusting a rotational phase between a crankshaft and a camshaft of an engine to advance or retard the phase of the cam angle with respect to the crank angle. A control device for an engine having a mechanism, wherein when it is determined that the engine is decelerating and fuel cut is being performed, the variable valve timing mechanism is locked at a predetermined reference position and the phase difference of the cam angle is determined. A lock position learning unit that performs lock position learning, and when the accelerator opening is greater than or equal to a set opening during the execution of the lock position learning or during the control transition to the target valve timing after completion, the engine And an ignition timing correction unit that corrects the ignition timing for a predetermined period.

  According to the present invention, when the lock position learning of the variable valve timing mechanism is ended by the driver's accelerator operation, or when the accelerator operation is performed by the driver during the control shift to the target valve timing after the lock position learning ends, the target valve timing is Acceleration response delay due to a temporary shortage of torque until reaching can be eliminated, and deterioration of drive feeling can be prevented.

Overall configuration diagram of engine with variable valve timing mechanism Time chart showing the relationship between lock position learning and ignition timing correction Flow chart of ignition timing correction routine Flow chart of other ignition timing correction routine

Embodiments of the present invention will be described below with reference to the drawings.
In FIG. 1, reference numeral 1 denotes an engine with a variable valve timing mechanism (hereinafter simply referred to as “engine”). In FIG. 1, the engine 1 is a horizontally opposed four-cylinder engine in which a cylinder block 1a is divided into two banks on the left and right (the left bank on the right side and the right bank on the left side) centering on the crankshaft 1b. .

  First, the intake / exhaust system of the engine 1 will be described. Cylinder heads 2 are provided in both the left and right banks of the cylinder block 1a of the engine 1, and an intake port 2a and an exhaust port 2b are formed in each cylinder head 2 for each cylinder.

  An intake manifold 3 is communicated with each intake port 2 a of the cylinder head 2, and an injector 11 is disposed immediately upstream of the intake port 2 a of each cylinder of the intake manifold 3. The intake manifold 3 communicates with the throttle chamber 5 through an air chamber 4 in which intake passages of the cylinders gather.

  A throttle valve 5 a that is driven by a throttle actuator 10 is interposed in the throttle chamber 5. Further, an air cleaner 7 is attached upstream of the throttle chamber 5 via an intake pipe 6, and the chamber 8 is communicated with an air intake passage connected to the air cleaner 7.

  On the other hand, an exhaust manifold 14 is communicated with each exhaust port 2 b of the cylinder head 2, and an exhaust pipe 15 is communicated with a collective portion of the exhaust manifold 14. A catalytic converter 16 is interposed in the exhaust pipe 15 and communicates with the muffler 17.

  Each cylinder of the cylinder head 2 is provided with a spark plug 12 that exposes the discharge electrode to the combustion chamber. Each spark plug 12 is connected to an ignition coil 13 with a built-in igniter.

  Next, the valve train of the engine 1 will be described. An intake cam shaft 19 and an exhaust cam shaft 20 are disposed in each cylinder head 2 of the left and right banks of the engine 1, and the rotation of the crankshaft 1 b is transmitted to the cam shafts 19 and 20. The transmission of rotation of the crankshaft 1b to the intake camshaft 19 and the exhaust camshaft 20 is performed by a crank pulley 21 fixed to the crankshaft 1b, a timing belt 22, an intake cam pulley 23 interposed in the intake camshaft 19, This is performed via an exhaust cam pulley 24 and the like fixed to the exhaust cam shaft 20. Each of the camshafts 19 and 20 is maintained at a rotation angle of 2 to 1 with the crankshaft 1b by the intake cam provided on the intake camshaft 19 and the exhaust cam provided on the exhaust camshaft 20. Based on this, the intake valve 25 and the exhaust valve 26 are driven to open and close.

  Further, between the intake cam shafts 19 and the intake cam pulleys 23 of the left and right banks, the intake cam pulleys 23 and the intake cam shafts 19 are rotated relative to each other to rotate the rotation phase (displacement angle) of the intake cam shaft 19 with respect to the crankshaft 1b. A variable valve timing mechanism 27 is provided for continuously changing. The variable valve timing mechanism 27 is a known hydraulically driven valve timing mechanism. In the present embodiment, the variable valve timing mechanism 27 is provided only on the intake camshaft 19 side of each bank. That is, the variable valve timing mechanism 27 is configured by housing a vane body connected to the intake camshaft 19 in a housing connected to the intake cam pulley 23, and relatively rotating the vane body by hydraulic pressure, thereby The relative rotation phase of the intake camshaft 19 with respect to the cam pulley 23 is changed, and the valve timing of the intake valve 25 with respect to the exhaust valve 26 is changed.

  The variable valve timing mechanism 27 of each bank is provided with an oil flow control valve 28 for adjusting the hydraulic pressure supplied from the oil pan 1c via an oil pump (not shown). The oil flow control valve 28 is composed of, for example, an electromagnetic spool valve or the like, and is duty-controlled by an electronic control unit (hereinafter abbreviated as “ECU”) 50 composed of a microcomputer or the like. The hydraulic pressure supplied to the hydraulic chamber defined and formed by the vane body is adjusted.

  That is, when the spool of the oil flow control valve 28 moves in the axial direction in proportion to the energized current by the duty control, the advance chamber (advance hydraulic chamber) and the retard chamber (retard operation) of the variable valve timing mechanism 27. The ports communicating with the hydraulic chamber) are switched, the flow direction of the oil is switched, and the opening of the passage is adjusted. As a result, the magnitude of the hydraulic pressure supplied to the advance chamber and retard chamber of the variable valve timing mechanism 27 is adjusted, and the opening / closing timing of the intake valve 25 is controlled to the advance or retard side.

  The variable valve timing mechanism 27 is a lock that locks the rotational phase of the camshaft at a phase corresponding to the predetermined timing in order to fix the valve timing at a predetermined timing in a low oil pressure state such as when the engine is started. A mechanism is provided. This lock mechanism is composed of, for example, a lock hole provided in the housing, and a lock pin provided in the vane body in a state of being biased in the direction of the lock hole by a spring or the like, and by engaging the lock pin and the lock hole, the housing The relative rotation of the vane body with respect to is mechanically locked. In the present embodiment, the engagement position between the lock pin and the lock hole is set so as to be locked at an intermediate position between the most retarded angle position and the most advanced angle position.

  Next, sensors for detecting the state of the engine 1 will be described. An intake air amount sensor 30 is provided immediately downstream of the air cleaner 7 of the intake pipe 6 for detecting parameters related to the intake air amount and fuel amount of the engine 1, and the amount of depression is detected by an accelerator pedal (not shown). An accelerator position sensor 31 is provided continuously.

  In addition, an oil temperature sensor 32 is exposed to the oil pan 1c and a water temperature sensor 34 is exposed to the cooling water passage 33 that communicates the left and right banks of the cylinder block 1a for detecting the operating state parameters of the engine 1. . Further, an air-fuel ratio sensor 35 is disposed on the upstream side of the catalytic converter 16.

  On the other hand, for detecting the operation position parameter of the engine 1, a crank angle sensor 37 is provided on the outer periphery of the crank rotor 36 that is attached to the crankshaft 1b, and is fixed to the rear end of the intake camshaft 19 of each bank. On the outer periphery of the cam rotor 39, cam position sensors 40 for cam position detection are respectively provided.

  The output signals from the above sensors are input to the ECU 50 and processed to detect the engine operating state. The ECU 50 processes signals from the sensors, switches, and the like according to a control program stored in advance, and the igniter, throttle actuator 10 and variable valve timing mechanism built in the injector 11 and ignition coil 13 described above. The control amount for the oil flow control valve 27 and the like is calculated, and engine control such as fuel injection control, ignition timing control, throttle control, and valve timing control is performed.

  Here, in the valve timing control, a target which is a control target value of a phase difference between the rotation angle of the crankshaft 1b and the rotation angle of the intake camshaft 19 based on the engine operating state, for example, the engine load and the engine speed. In addition to setting the valve timing, the actual rotation angle of the crankshaft 1b and the intake air are determined from the crank pulse indicating the crank angle output from the crank angle sensor 37 and the cam position pulse indicating the cam position output from the cam position sensor 40. An actual valve timing that is a phase difference from the actual rotation angle of the camshaft 19 is calculated. Then, the variable valve timing mechanism 27 is feedback-controlled through the oil flow control valve 28 so that the actual valve timing converges to the target valve timing.

  Further, the ECU 50 learns the lock position (reference position) of the variable valve timing mechanism 27 under a predetermined condition, and actual valve timing due to individual differences of the variable valve timing mechanism 27, the influence of temperature (such as engine thermal expansion), and the like. To prevent misalignment. As described above, in the present embodiment, the variable valve timing mechanism 27 is locked at an intermediate position between the most retarded angle position and the most advanced angle position, and learning is performed at this intermediate lock position. .

  This intermediate lock position is set aiming at an optimum point for reducing exhaust emission at the time of engine start, and is a position different from the advance amount during idling after the warm-up is completed. That is, when the engine is started, the engine is not warmed, so that the fuel is difficult to vaporize. Therefore, the lock position of the variable valve timing mechanism 27 is set to a more advanced side than the idling after the warm-up is completed, the intake port is opened early, and the exhaust gas is sent to the intake side to facilitate vaporization of the fuel, The exhaust emission is improved.

  In this case, if the lock position learning of the variable valve timing mechanism 27 is performed during the idle operation after the warm-up is completed, the idle operation may become unstable due to a decrease in charging efficiency. Therefore, the ECU 50 learns the intermediate lock position of the variable valve timing mechanism 27 at the time of fuel cut during coasting driving (at the time of deceleration fuel cut) that hardly affects the combustion state (it is difficult to affect the engine generated torque). It has a function as a lock position learning unit.

  In addition, as shown in FIG. 2, when the accelerator is depressed by the driver during the lock position learning and the accelerator opening is equal to or larger than the set opening (for example, the accelerator opening is equal to or greater than 0%) as shown in FIG. ), The lock position learning is finished, the lock is released, and then the control to the target advance amount is started. At this time, the engine torque is temporarily insufficient with respect to the driver's accelerator operation from the coasting running, and there is a possibility that the drive feeling is deteriorated. This is the same when the driver depresses the accelerator pedal during the control shift to the target valve timing after the lock position learning is completed, and the response to the driver's accelerator depressing is lowered, leading to deterioration of drive feeling. There is a fear. Here, when the control transition to the target valve timing is completed after the lock position learning is completed, the unlocking is not yet completed after the lock position learning is completed, or the lock is released after the lock position learning is completed, Including the situation where the timing is in the locked position (the situation before the completion of the control shift to the target valve timing).

  Therefore, the ECU 50 determines that the driver depresses the accelerator pedal during the lock position learning at the time of deceleration fuel cut and the driver depresses the accelerator pedal when the lock is released or during the control shift to the target valve timing after the lock position learning ends. When the engine is depressed, a function of an ignition timing correction unit that compensates for a shortage of torque by temporarily correcting the ignition timing simultaneously with control to the target advance amount is also provided. That is, as shown in FIG. 2, the actual valve timing (actual advance amount; phase indicated by a broken line in FIG. 2) is obtained when the lock position learning accompanying the depression of the accelerator is completed or when the accelerator is depressed after the completion of the lock position learning. Until the target valve timing (target advance amount) is reached, the ignition timing is advanced according to the difference between the actual advance amount and the target advance amount, thereby eliminating the torque shortage.

  Specifically, the accelerator pedal is depressed while the valve timing is still in the lock position during the lock position learning or after the lock position learning is completed, and the target advance amount at that time is located on the advance side relative to the reference position. In this case, the ignition timing is temporarily advanced according to the difference between the reference position and the target advance amount (or the difference between the actual advance amount and the target advance amount). This makes it possible to quickly compensate for the temporary torque shortage due to the control delay to the target advance amount after unlocking the driver's accelerator depression, by the ignition timing advance, and the deterioration of the drive feeling due to the reduced response Can be avoided.

  However, if the target advance amount when the accelerator is depressed is on the retard side compared to the reference position, the difference between the reference position and the target advance amount (or the difference between the actual advance amount and the target advance amount) In response, the ignition timing is temporarily retarded. This is to prevent knocking and excessive increase in torque.

  Specifically, the ECU 50 suppresses response deterioration at the time of shifting from the end of the lock position learning to the target advance amount control by the ignition timing correction routine shown in the flowchart of FIG. Next, the ignition timing correction routine will be described.

  The ignition timing correction routine shown in FIG. 3 is a program process that is periodically executed when the coast lock position learning is started. First, in step S1, it is checked whether or not the coast lock position learning is finished. If the lock position learning has not been completed, this routine is exited, and if the driver depresses the accelerator pedal from the signal of the accelerator position sensor 31 and the accelerator opening changes by a set value (for example, 0%) or more, the lock is performed. It is determined that the position learning has been completed, and the process proceeds to step S2. In step S2, the current actual valve timing (actual advance amount) A is detected based on the outputs of the crank angle sensor 37 and the cam position sensor 40, and the current engine operating state, for example, engine load and engine speed, is detected. Based on this, a target valve timing (target advance amount) B is calculated. Next, the process proceeds to step S3, and it is checked whether or not the time during which the absolute value | A−B | of the difference between the actual valve timing A and the target valve timing B is equal to or less than the set value α has passed the set time Ts. .

  The set value α is a phase difference obtained in advance by experiments or simulations, and is a value close to zero. If | A−B |> α and the phase difference is large, the process proceeds from step S3 to step S4, and ignition timing correction is performed. Also, the set time Ts for the duration of the state of | A−B | ≦ α is a time when the actual phase reaches the target phase after the end of the lock position learning and it can be considered that the torque reduction has been eliminated. Obtained by simulation or the like. Accordingly, even when the time in which | A−B | ≦ α has not reached the set time Ts, the routine proceeds from step S3 to step S4 to correct the ignition timing.

  The ignition timing correction in step S4 is performed by determining a correction value set in advance according to the difference between the current valve timing and the target valve timing using a map or the like. By performing this ignition timing correction, it is possible to eliminate a temporary shortage of engine torque when controlling from the end of the lock position learning to the target advance amount. Thereafter, the routine is exited and the process returns to the start. In step S3, when the phase difference | A−B | becomes equal to or smaller than the set value α and the state of | A−B | ≦ α has passed the set time Ts, the actual valve timing is Since there is no torque shortage due to convergence near the target valve timing, the ignition timing correction is terminated in step S5, and the normal ignition timing corresponding to the engine operating state is restored.

  Thus, in the present embodiment, when the accelerator pedal is depressed by the driver during learning of the lock position of the variable valve timing mechanism 27, the ignition timing is corrected for a predetermined period. As a result, it is possible to make up for a temporary shortage of engine torque when shifting from the end of lock position learning to the target valve timing, and to prevent deterioration of drive feeling.

  As shown in the flowchart of FIG. 4, the ignition timing correction routine of FIG. 3 is slightly changed, and in step S1 ′, it is determined whether or not the accelerator opening has changed by a set value or more. By executing the routine every time the position learning is completed, the ignition timing can be similarly corrected for a predetermined period even in the situation where the shift to the target valve timing is completed after the lock position learning is completed. In this case as well, it is possible to compensate for a temporary shortage of engine torque when shifting to the target valve timing after the end of the lock position learning, and to prevent the drive feeling from deteriorating.

1 engine
1b Crankshaft 5a Throttle valve 10 Throttle actuator 19 Intake camshaft 20 Exhaust camshaft 27 Variable valve timing mechanism 28 Oil flow control valve 50 Electronic control unit (lock position learning unit, ignition timing correction unit)

Claims (4)

An engine control device having a variable valve timing mechanism that adjusts a rotation phase between a crankshaft and a camshaft of an engine to advance or retard the phase of the cam angle with respect to the crank angle,
When it is determined that the engine is decelerating and fuel cut is being performed, the lock position learning is performed in which the variable valve timing mechanism is locked at a predetermined reference position to learn the cam angle phase difference. The learning department,
An ignition timing correction unit that corrects the ignition timing of the engine for a predetermined period when the accelerator opening is equal to or greater than a set opening during execution of the lock position learning or during control shift to the target valve timing after completion of the lock position learning; An engine control device comprising: an engine control device;   2. The engine control device according to claim 1, wherein the ignition timing correction unit corrects the ignition timing in accordance with a difference between a current actual valve timing and a target valve timing.   3. The engine according to claim 1, wherein the ignition timing correction unit corrects the ignition timing when the absolute value of the difference between the current actual valve timing and the target valve timing is larger than a set value. Control device.   The ignition timing correction unit ends the correction of the ignition timing when a set time has elapsed when an absolute value of a difference between a current actual valve timing and a target valve timing is smaller than a set value. The engine control device according to 1 or 2.

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