JP6051793B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine having a variable valve timing mechanism.

  For example, in Patent Document 1, in transient operation, the timing at which the actual throttle valve opening changes after the accelerator opening changes, and the timing at which the actual valve timing changes after the target valve timing changes. Is disclosed in which the actual load (actual intake pressure) that changes in accordance with the actual throttle valve opening and the actual valve timing are synchronized and changed substantially simultaneously. . In Patent Document 1, since the actual valve timing can be changed almost simultaneously with the actual load, it is possible to prevent deterioration of the combustion state due to a response delay of the variable valve timing mechanism during transient operation. It has become.

JP 2008-208741 A

  However, the change in the actual intake pressure (actual load) due to the actual change in the throttle valve opening arrives in the cylinder with a delay corresponding to the volume of the intake system downstream of the throttle valve. The intake air amount corresponding to the target torque may not be obtained simply by substantially matching the timing at which the throttle valve opening changes and the timing from when the target valve timing changes until the actual valve timing changes. There is.

Therefore, the present invention provides a variable valve so that when the target torque changes, the timing at which the suction negative pressure begins to change due to the change in the opening of the throttle valve is synchronized with the timing at which the valve timing of the engine valve starts to change. to control the timing mechanism and a throttle valve, during acceleration the target torque is increased, so as to correct larger than that when the steady state point operation target throttle valve opening degree is the target torque the same constant, the during deceleration of the target torque is reduced is the target throttle valve opening degree and correcting to be smaller than when the stationary state.

  According to the present invention, the response delay of the suction negative pressure caused by the volume of the intake system from the throttle valve to the cylinder can be corrected (improved), so that the operating performance of the internal combustion engine is not deteriorated during the transition. It becomes possible to control the internal combustion engine.

1 is a system diagram showing the overall configuration of an internal combustion engine to which the present invention is applied. The block diagram which showed the flow of control at the time of the transition in which target torque changes. The block diagram which showed the procedure at the time of calculating opening correction amount. The timing chart which shows the control at the time of the transition in which a target torque changes. Explanatory drawing which showed typically the correlation of the valve timing of an intake valve, and an intake negative pressure.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a system diagram showing the overall configuration of an internal combustion engine 1 to which the present invention is applied.

  Air (intake air) is introduced into the combustion chamber 2 of the internal combustion engine 1, which is a spark ignition gasoline engine for vehicles, through an intake passage 3. The combustion chamber 2 includes a cylinder head 4, a cylinder block 5, and a piston 7 that fits into a cylinder 6 of the cylinder block 5. Exhaust gas is discharged from the combustion chamber 2 through the exhaust passage 8. A spark plug 9 is provided for each combustion chamber 2 of each cylinder.

  The intake passage 3 includes an intake port 10 for each cylinder formed in the cylinder head 4 and an intake manifold 11 connected to each intake port 10.

  The intake manifold 11 has a branch portion 12 connected to an intake port of each cylinder, and a collector portion 13 located on the upstream side of the branch portion 12.

  The collector unit 13 is provided with an intake pressure sensor 14 that detects the intake pressure in the collector unit 13.

  An electrically controlled throttle valve 15 driven by an electric motor (not shown) is disposed upstream of the intake manifold 11. The opening degree of the throttle valve 15 is detected by a throttle opening degree sensor 16.

  The intake port 10 of each cylinder is provided with a fuel injection valve 17 so as to inject and supply fuel for each cylinder, and an intake valve 18 is provided at the downstream end thereof.

  The exhaust passage 8 includes an exhaust port 19 for each cylinder formed in the cylinder head 4 and an exhaust manifold 20 connected to each exhaust port 19. An exhaust valve 21 is provided at the upstream end of the exhaust port 19 of each cylinder. An exhaust purification catalyst 22 is provided on the downstream side of the exhaust manifold 20.

  In this embodiment, the valve mechanism on the intake valve 18 side and the valve mechanism on the exhaust valve 21 side are both known variable valve timing mechanisms 25 that can change the valve timing.

  The variable valve timing mechanism 25 can continuously delay the phase of the lift center angle of the engine valve (intake valve 18 or exhaust valve 21) with respect to the rotation phase of the crankshaft 23. The lift center angle of the valve lift is delayed. That is, by the variable valve timing mechanism 25, the valve opening timing and the valve closing timing of the engine valve can be changed by advancing or retarding the whole without changing the lift characteristic curve itself. .

  The variable valve timing mechanism 25 a on the intake valve 18 side in this embodiment changes the valve timing of the intake valve 18 by controlling the hydraulic pressure supplied by the solenoid valve 26. The control state of the variable valve timing mechanism 25 a is detected by an intake camshaft sensor 28 that responds to the rotational position of the intake camshaft 27. The intake camshaft sensor 28 can detect the opening timing and closing timing of the intake valve 18.

  The variable valve timing mechanism 25b on the exhaust valve 21 side in this embodiment changes the valve timing of the exhaust valve 21 by controlling the hydraulic pressure supplied by the solenoid valve 30. The control state of the variable valve timing mechanism 25 b is detected by an exhaust camshaft sensor 32 that responds to the rotational position of the exhaust camshaft 31. The exhaust camshaft sensor 32 can detect the opening timing and closing timing of the exhaust valve 21.

  In addition, as such a variable valve timing mechanism 25, a type using a vane, a type using a helical spline, and the like are known, but a detailed description thereof is omitted.

  Detection signals detected by the intake pressure sensor 14, the throttle opening sensor 16, the intake camshaft sensor 28, and the exhaust camshaft sensor 32 described above are input to an ECU (engine control unit) 35.

  The ECU 35 incorporates a microcomputer and performs various controls of the internal combustion engine 1, and performs processing based on signals from various sensors. In addition to the sensors described above, these various sensors include an air flow meter 36 that detects the intake air amount, a crank angle sensor 37 that can detect the engine rotational speed together with the crank angle, and an accelerator pedal (not shown). A signal is input from an accelerator opening sensor 38 or the like that detects the amount of depression (accelerator opening).

  Based on these detection signals, the ECU 35 determines the injection amount and injection timing of the fuel injection valve 17, the ignition timing by the ignition plug 9, the opening of the throttle valve 15, the intake valve 18 by the variable valve timing mechanisms 25a and 25b, The valve timing of the exhaust valve 21 is controlled.

  When the variable valve timing mechanism 25 capable of changing the valve timing is applied to the valve operating mechanism of the engine valve (the intake valve 18 or the exhaust valve 21) as in the present embodiment, the combustion chamber 2 (cylinder 6) The air amount (intake air amount) is controlled by both the opening degree of the throttle valve 15 and the valve timing of the engine valve.

  Therefore, if either the opening degree of the throttle valve 15 or the valve timing deviates from the target value, the amount of air actually taken into the combustion chamber 2 (cylinder 6) changes, and the combustion state is relatively As a result, the torque actually generated from the internal combustion engine (the output torque of the internal combustion engine) deviates from the target torque.

  Here, the change in the intake negative pressure due to the change in the opening of the throttle valve 15 is caused by the volume of the intake system downstream from the throttle valve 15 to the combustion chamber 2 (cylinder 6) (the intake manifold 11 and the intake air of each cylinder). The combustion chamber 2 (cylinder 6) is reached with a delay of the volume of the port 10). Therefore, at the time of transition, the opening degree of the throttle valve 15 is changed only by synchronizing the timing at which the suction negative pressure starts to change due to the opening degree change of the throttle valve 15 and the timing at which the valve timing of the intake valve 18 starts to change. However, there is a possibility that the intake air amount corresponding to the target torque cannot be obtained because the change in the suction negative pressure does not follow.

  Therefore, in the present embodiment, at the time of transition in which the target torque changes, the timing at which the suction negative pressure on the downstream side of the throttle valve 15 starts to change due to the change in the opening of the throttle valve 15 and the valve timing at the intake valve 18 start to change. The variable valve timing mechanism 25a and the throttle valve 15 are controlled so that the timing is synchronized, and the target opening degree of the throttle valve 15 is corrected to increase or decrease according to the transient state. That is, at the time of acceleration at which the target torque increases, the amount of increase in the suction negative pressure is increased by correcting the target torque so that the opening of the throttle valve 15 is larger than that in the steady state. Further, at the time of deceleration at which the target torque decreases, the amount of decrease in the suction negative pressure is increased by correcting the target torque so that the opening of the throttle valve 15 becomes smaller than that in the steady state.

  This makes it possible to correct (improve) the response delay of the change in the intake negative pressure caused by the volume of the intake system from the throttle valve 15 to the combustion chamber 2 (cylinder 6) during the transition, and deteriorate the driving performance. It becomes possible to control the internal combustion engine 1 without this.

FIG. 2 is a block diagram showing the flow of control during a transition in which the target torque changes.
In S1, the target torque is calculated according to the accelerator opening. In S2, the amount of change in the target torque calculated in S1 is limited so that the change in the opening of the throttle valve 15 does not exceed the response limit of the throttle valve 15 even if the throttle opening correction described later is performed. To do. That is, in S2, the control target torque is calculated by correcting the target torque calculated in S1 so as not to exceed the response limit of the throttle valve 15. This prevents the actual opening of the throttle valve 15 from following the target opening of the throttle valve 15, and the response of the actual suction negative pressure to the response of the target suction negative pressure. It is possible to accurately follow the performance.

  In S3, the target valve timing of the intake valve 18 is calculated based on the control target torque calculated in S2.

  In S4, the target opening of the throttle valve 15 is calculated based on the control target torque calculated in S2.

  In S5, the final opening degree is calculated by correcting the target opening degree of the throttle valve 15 calculated in S4 using the opening degree correction amount (described later) of the throttle valve 15 calculated in S6.

  In S7, dead time correction is performed so that the timing at which the intake negative pressure starts to change and the timing at which the valve timing of the intake valve 18 starts to change are synchronized. That is, the delay time from when the control command for changing the valve timing is issued to the variable valve timing mechanism 25a until the valve timing of the intake valve 18 actually starts to change is calculated, and the opening degree of the throttle valve 15 is set to the final target opening. After the control command is issued, the timing at which the suction negative pressure on the downstream side of the throttle valve 15 actually starts to change and the control command with the valve timing of the intake valve 18 as the target valve timing are issued, and then the intake valve 18 is actually The timing for driving the variable valve timing mechanism 25a and the throttle valve 15 is calculated so that the timing at which the valve timing begins to change is synchronized. Since the throttle valve 15 is more responsive than the variable valve timing mechanism 25a, in this embodiment, when the target torque is changed, a control command for changing the valve timing is issued to the variable valve timing mechanism 25a. A control command to change the opening degree is issued to the throttle valve 15. The variable valve timing mechanism 25 in the present embodiment is hydraulically driven. However, even in the case of an electrically controlled variable valve timing mechanism driven by an electric motor or the like, the response is higher than that of the throttle valve 15. Will be late.

  In S8 and S9, the variable valve timing mechanism 25a and the throttle valve 15 are driven so that the timing at which the intake negative pressure begins to change and the timing at which the valve timing of the intake valve 18 begins to change are synchronized. Further, the throttle valve 15 is controlled so that the final target opening is corrected using an opening correction amount (described later).

  FIG. 3 is a block diagram showing a procedure for calculating the opening correction amount of S6 described above. In S61, a response cooperative control permission determination is performed. That is, the amount of correction of the opening of the throttle valve 15 is calculated during the transition, and the response delay of the change in intake negative pressure caused by the volume of the intake system from the throttle valve 15 to the combustion chamber 2 (cylinder 6) is corrected (improved). It is determined whether or not the situation is acceptable.

  Specifically, for example, when the intake negative pressure is unstable, when the valve timing of the intake valve 18 does not change, or when the battery voltage of the in-vehicle battery (not shown) is less than a predetermined voltage, the response cooperative control Is now prohibited.

  When the suction negative pressure is unstable, if the correction of the target opening of the throttle valve 15 at the time of transition is allowed, the time until the steady stable state is increased. In order to avoid such a situation, Response coordination control is prohibited. For example, immediately after the internal combustion engine 1 is started, response negative control is prohibited because the suction negative pressure is unstable.

  When the target torque changes but the valve timing of the intake valve 18 does not change, there is no target to match the timing at which the intake negative pressure starts to change, and therefore response cooperative control is prohibited. As a result, when the throttle valve 15 is an electrically controlled throttle valve, the power consumption can be reduced by not performing the opening degree correction of the throttle valve 15.

  Further, when the throttle valve 15 is an electrically controlled throttle valve, if the correction of the target opening of the throttle valve 15 at the time of transition is allowed when the battery voltage is lowered, the actual opening with respect to the target opening of the throttle valve 15 is allowed. In a state where the followability of the opening degree is deteriorated due to insufficient voltage, the drivability may be deteriorated due to unintended torque fluctuation by correcting the target opening degree of the throttle valve 15 to increase or decrease according to the transient state. Therefore, in order to avoid such a situation, response cooperative control is prohibited.

  As a result of the response cooperative control permission determination, if the response cooperative control is permitted, the process proceeds to S62, and if the response cooperative control is not permitted, the opening correction amount of the throttle valve 15 is not calculated. That is, when the response cooperative control is not permitted, the target opening of the throttle valve 15 calculated in S4 is set as the final target opening in S5 described above.

  In S62, the change amount of the target intake air amount at the time of transition determined from the engine speed and the target torque is calculated.

  In S63, the intake volume downstream of the throttle valve 15 (the volume of the intake system from the throttle valve 15 to the combustion chamber 2) is read.

  In S64, the opening correction amount of the throttle valve 15 is calculated based on the target intake air amount at the time of transition calculated in S62 and the intake volume detected in S63. The opening correction amount is set to increase as the amount of change in the target intake air amount during the transition calculated in S62 increases.

  In this embodiment, the intake passage length on the downstream side of the throttle valve 15 is constant. For example, when the substantial intake pipe length of each cylinder can be switched according to the operating state, the intake passage length depends on the operating state. The substantial intake volume downstream of the throttle valve 15 changes. Thus, when applied to a variable intake system that changes the substantial intake volume downstream of the throttle valve 15 in accordance with the operating state, the opening correction amount increases as the intake volume detected in S63 increases. Set to be larger.

  By setting the opening correction amount in this way, it becomes possible to correct (improve) the response delay of the change in the intake negative pressure regardless of the operating region of the internal combustion engine and the intake volume.

FIG. 4 is a timing chart showing control at the time of transition in which the target torque changes. When the target torque increases at time t1, the opening correction amount of the throttle valve 15 changes. Then, the final target opening of the throttle valve 15 is corrected to increase by this opening correction amount. At the time of acceleration, the opening correction amount of the throttle valve 15 is set so that the opening of the throttle valve 15 becomes larger than the steady state with respect to the target torque, and the increase amount of the suction negative pressure is increased. The characteristic line A shown by a broken line in FIG. 4 is a diagram illustrating the opening of the throttle valve 15 for realizing the target torque in the steady state.

  Here, a control command is issued to the variable valve timing mechanism 25a so that the valve timing of the intake valve 18 becomes a target valve timing corresponding to the control target torque at time t1. As a result, the actual valve timing of the intake valve 18 starts to change at time t2. That is, the time from time t1 to time t2 is the delay time (dead time) of the variable valve timing mechanism 25a. This delay time is calculated in advance according to, for example, whether the engine speed, the oil temperature, and the direction in which the variable valve timing mechanism 25a is controlled are the advance side or the retard side.

  Then, from the delay time of the variable valve timing mechanism 25a calculated in advance, the timing at which the valve timing of the intake valve 18 actually begins to change at time t2 and the downstream side of the throttle valve 15 due to the change in the opening of the throttle valve 15 The throttle valve 15 is controlled so that the timing at which the suction negative pressure actually starts to change is synchronized.

  When the target torque decreases at time t4, the opening correction amount of the throttle valve 15 changes. Then, the final target opening of the throttle valve 15 is corrected to decrease by this opening correction amount. At the time of deceleration, the opening degree correction amount of the throttle valve 15 is set so that the opening degree of the throttle valve 15 becomes smaller than the steady state and the reduction amount of the suction negative pressure becomes larger than the target torque.

  A control command is issued to the variable valve timing mechanism 25a so that the valve timing of the intake valve 18 becomes a target valve timing corresponding to the control target torque at time t4. As a result, the actual valve timing of the intake valve 18 starts to change at time t5.

  Then, from the delay time of the variable valve timing mechanism 25a calculated in advance, the timing at which the valve timing of the intake valve 18 starts to change at time t5 and the downstream side of the throttle valve 15 due to the change in the opening of the throttle valve 15 The throttle valve 15 is controlled so that the timing at which the suction negative pressure actually starts to change is synchronized.

At the time of excessive target torque changes, in this embodiment, since the target opening of the throttle valve 1 5 is corrected by the opening correction amount in accordance with the transient state, the combustion chamber 2 (the cylinder from the throttle valve 15 6) To change the suction negative pressure with higher responsiveness than when the response delay of the change of the suction negative pressure due to the volume of the intake system leading to 6) is not taken into consideration (characteristic line B shown by the broken line in FIG. 4). Is possible.

  FIG. 5 is an explanatory view schematically showing the correlation between the valve timing of the intake valve 18 and the intake negative pressure. The thin solid line connecting the plots and the plots in FIG. 5 indicates a combination of the valve timing and the intake negative pressure of the intake valve 18 that achieves the target torque in the steady state. In a steady state, the combination of the valve timing of the intake valve 18 and the suction negative pressure changes along a thin solid line connecting the plots.

  The broken line in FIG. 5 indicates the timing at which the valve timing of the intake valve 18 actually begins to change without correcting the target opening of the throttle valve 15 in accordance with the transient state during a transition in which the target torque changes. This is a comparative example showing a change in the combination of the suction negative pressure and the valve timing of the intake valve 18 when the timing at which the suction negative pressure actually starts to change is simply synchronized. In this comparative example, since the target opening degree of the throttle valve 15 is not corrected to increase or decrease according to the transient state, the change in the valve timing of the intake valve 18 becomes earlier than the change in the intake negative pressure in the transient state. The combination of the valve timing 18 and the suction negative pressure greatly deviates from the combination of the valve timing of the intake valve 18 and the suction negative pressure that achieves the target torque in the steady state.

  On the other hand, as in the above-described embodiment, at the time of transition in which the target torque changes, the timing at which the valve timing of the intake valve 18 actually starts to change and the timing at which the intake negative pressure starts to change are synchronized, When the target opening of the throttle valve 15 is corrected to increase or decrease in accordance with the transient state, the combination of the valve timing of the intake valve 18 and the suction negative pressure changes as shown by a bold solid line in FIG. That is, in this embodiment, since the change in the suction negative pressure during the transition is corrected to correspond to the change in the valve timing of the intake valve 18, the combination of the suction negative pressure during the transition and the valve timing of the intake valve 18 is It is possible to approach a combination that achieves the target torque in a steady state. Therefore, the driving performance at the time of transition can be brought close to the driving performance at the steady state, and the driving performance can be relatively improved. Further, since the suction negative pressure that changes slowly is corrected in accordance with the valve timing that changes quickly, it is possible to promptly respond to the driving request of the driver.

  At the time of deceleration at which the target torque decreases, the target opening of the throttle valve 15 is controlled so as to be fully closed and the intake air amount becomes zero. However, the throttle valve 15 is actually fully closed. It is not open and is in a slightly opened state. Therefore, at the time of deceleration at which the target torque decreases, controlling the throttle valve 15 so as to increase the time area of the throttle valve opening is advantageous in improving the response of the suction negative pressure. Specifically, the throttle valve 15 is opened from the fully closed state so that the amount of air that has passed through the throttle valve 15 is canceled during the period when the final target opening of the throttle valve 15 is fully closed. What is necessary is just to delay timing.

  In the present embodiment, both the valve mechanisms on the intake valve 18 side and the exhaust valve 21 side are the variable valve timing mechanism 25, but both of the valve mechanisms on the intake valve 18 side and the exhaust valve 21 side are There is no need for the variable valve timing mechanism 25. For example, only the valve mechanism on the intake valve 18 side is used as the variable valve timing mechanism 25, and the valve lift characteristic on the valve mechanism on the exhaust valve 21 side is always constant. It may be a direct acting type.

  Further, in the above-described embodiment, the timing at which the intake negative pressure starts to change and the timing at which the intake valve 18 starts to change are synchronized, and the target opening of the throttle valve 15 is corrected to increase or decrease according to the transient state. However, the timing at which the suction negative pressure starts to change and the timing at which the valve timing of the exhaust valve 21 starts to change are synchronized, and the target opening of the throttle valve 15 is corrected to increase or decrease according to the transient state. Good. Then, the timing at which the intake negative pressure begins to change may be synchronized with the timing at which the valve timings of the intake valve 18 and the exhaust valve 21 start to change.

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Combustion chamber 6 ... Cylinder 15 ... Throttle valve 18 ... Intake valve 25a ... Variable valve timing mechanism 35 ... ECU

Claims (9)

A variable valve timing mechanism capable of changing the valve timing of the engine valve, a throttle valve for adjusting the intake air amount, and target torque calculation means for calculating a target torque required for the internal combustion engine according to the operating state ,
In a control device for an internal combustion engine that controls the valve timing of the engine valve and the opening of the throttle valve according to the target torque,
When the target torque changes, the variable valve timing mechanism is arranged so that the timing at which the intake negative pressure starts to change due to the change in the throttle valve opening is synchronized with the timing at which the valve timing of the engine valve starts to change. And controlling the throttle valve,
Said at acceleration target torque is increased, so as to correct larger than that when the steady state point operation target throttle valve opening degree is the target torque the same becomes constant,
During deceleration the target torque is reduced, the control device for an internal combustion engine, characterized by correcting the target throttle valve opening degree smaller than when the stationary state. Opening correction amount of the throttle valve at the time of the transient is calculated according to the engine rotational speed and the target torque, larger the amount of change in the target intake air amount at the transient time determined from the engine speed and the target torque increases The control apparatus for an internal combustion engine according to claim 1, wherein the control apparatus is set to be The internal combustion engine includes a variable intake mechanism that can change the intake flow path length on the downstream side of the throttle valve,
Opening correction amount of the throttle valve at the time of the transient is calculated according to the intake air volume of the engine speed and the target torque and the throttle valve downstream side, the target intake air at the transient time determined from the engine speed and the target torque 2. The control device for an internal combustion engine according to claim 1, wherein the control device is set to increase as the amount of change in the amount increases or as the intake volume increases. The control of the internal combustion engine according to any one of claims 1 to 3, wherein an amount of change in the target torque is limited so that a change in the target throttle valve opening does not exceed a response limit of the throttle valve. apparatus.   5. The control apparatus for an internal combustion engine according to claim 1, wherein the time area of the throttle valve opening is increased during deceleration.   6. The control apparatus for an internal combustion engine according to claim 1, wherein correction of the target throttle valve opening is permitted when the suction negative pressure is in a stable state.   The control device for an internal combustion engine according to any one of claims 1 to 6, wherein correction of the target throttle valve opening is permitted when the valve timing of the engine valve changes.   The internal combustion engine according to any one of claims 1 to 7, wherein the throttle valve is an electric throttle valve, and permits correction of the target throttle valve opening when the battery voltage is equal to or higher than a predetermined voltage. Engine control device. A variable valve timing mechanism capable of changing the valve timing of the engine valve, a throttle valve for adjusting the intake air amount, and target torque calculation means for calculating a target torque required for the internal combustion engine according to the operating state ,
  In a control device for an internal combustion engine that controls the valve timing of the engine valve and the opening of the throttle valve according to the target torque,
  The internal combustion engine includes a variable intake mechanism that can change the intake flow path length on the downstream side of the throttle valve,
  When the target torque changes, the variable valve timing mechanism is arranged so that the timing at which the intake negative pressure starts to change due to the change in the throttle valve opening is synchronized with the timing at which the valve timing of the engine valve starts to change. And controlling the throttle valve,
  During acceleration when the target torque increases, the target throttle valve opening is corrected so as to be larger than in the steady state where the operating point is the same and the target torque is constant,
  At the time of deceleration at which the target torque decreases, the target throttle valve opening is corrected to be smaller than that in the steady state,
  The throttle valve opening correction amount at the time of transition is calculated according to the engine speed, the target torque, and the intake volume downstream of the throttle valve, and the target intake air at the time of transition determined from the engine speed and the target torque. A control device for an internal combustion engine, which is set to increase as the amount of change in the amount increases or as the intake volume increases.

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