JP2007100662A - Control device of internal combustion engine for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain longitudinal vibration of a vehicle (torsional vibration of a vehicle driving system) when accelerating from a speed reduction-fuel cut state. <P>SOLUTION: A suction air quantity of an engine is increasingly corrected to increase engine output for a torsional vibration period after acceleration, and an ignition timing advance margin of the ignition timing is secured by correcting the ignition timing for an ignition timing delay (HOS1) to offset an increase in the engine output. The ignition timing is corrected for an ignition timing advance (HOS2) when a rate of change is negative in response to the rate of change ΔNe of an engine speed for the torsional vibration period. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine for a vehicle for suppressing longitudinal vibrations of the vehicle during acceleration of the vehicle.

In the technique described in Patent Document 1, during a predetermined time immediately after acceleration detection, the ignition timing is retarded when the positive rate of change of the engine speed is equal to or greater than a predetermined value, whereby vehicle longitudinal vibration (vehicle Torsional vibration of the drive system).
In other words, the excitation force of the longitudinal vibration of the vehicle increases when the rate of change of the engine speed changes by a predetermined value or more in the positive direction, so that the vibration is reduced by temporarily reducing the engine output torque at this moment. ing.
JP-A-8-028419

  By the way, in order to suppress the longitudinal vibration of the vehicle, in addition to reducing the engine output torque when the engine speed change rate is positive, the engine output torque is increased when the engine speed change rate is negative. It is effective to make it. That is, when the drive shaft of the vehicle receives the reaction force of the drive system and is twisted back, it is possible to cancel the torsional vibration by increasing the output torque of the engine.

However, in the region where the operation is performed at the MBT ignition timing, the torque cannot be increased even if the ignition timing is advanced. In addition, when the engine is operated at the ignition timing at the knocking limit, knocking occurs when the vehicle is advanced, so that it is difficult to increase the torque by the ignition timing advance.
In view of such a situation, the present invention makes it possible to accurately suppress the longitudinal vibration of the vehicle at the time of acceleration by using the torque increase due to the ignition timing advance by securing the advance angle margin of the ignition timing. With the goal.

  Therefore, in the present invention, the intake air amount is increased and corrected so as to increase the engine output for a predetermined period after acceleration detection, while the ignition timing is retarded so as to offset the increase in the engine output. Then, in this state, the ignition timing is advanced according to the change rate of the engine speed when the change rate is negative.

  According to the present invention, the ignition timing can be retarded by the amount corresponding to the increase correction of the intake air amount, and the advance margin of the ignition timing can be ensured. In this state, when the rate of change of the engine speed is negative, the longitudinal timing of the vehicle (torsional vibration of the drive system) can be suppressed by correcting the ignition timing.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a system diagram of a vehicle internal combustion engine (engine) showing an embodiment of the present invention.
An engine 1 mounted on a vehicle is provided with an electrically controlled throttle valve 3 for intake air amount control in an intake passage 2 thereof. Each cylinder is provided with a fuel injection valve 4 and a spark plug 5.
The output side of the engine 1 is connected to a drive shaft 7 of the vehicle via a transmission 6.

The operations of the electric throttle valve 3, the fuel injection valve 4, and the spark plug 5 are controlled by an engine control unit (ECU) 10.
Signals are input to the ECU 10 from various sensors.
The accelerator pedal sensor 11 detects the depression amount (accelerator opening) APO of the accelerator pedal and outputs a corresponding signal.

The crank angle sensor 12 outputs a signal synchronized with the rotation of the crankshaft of the engine 1, and can detect the engine speed Ne from this signal.
The air flow meter 13 detects the intake air amount Qa of the engine 1 and outputs a corresponding signal.
The vehicle speed sensor 14 detects a vehicle speed (output shaft rotation speed of the transmission 6) VSP and outputs a corresponding signal.

  Here, the ECU 10 determines a target air amount mainly based on the accelerator opening APO, controls the opening of the electric throttle valve 3 so as to obtain the target air amount, and controls the intake air amount Qa controlled thereby. The fuel injection amount of the fuel injection valve 4 is controlled so that the air-fuel ratio becomes the same. Then, the air-fuel mixture of the intake air and the injected fuel is ignited by the spark plug 5 and burned to obtain the engine output.

  Further, during a predetermined deceleration operation, fuel cut is performed to stop fuel injection of the fuel injection valve 4 to reduce fuel consumption. Specifically, the fuel is operated under the condition (fuel cut start condition) that the accelerator opening APO = 0 (the foot is released from the accelerator pedal) and the engine speed Ne is equal to or higher than a predetermined fuel cut speed. When the accelerator opening APO> 0 is reached by the driver's accelerator operation or the engine speed Ne is equal to or lower than the predetermined fuel recovery speed, the fuel cut ends and the fuel recovery (fuel recovery (fuel Reinjection).

Furthermore, when acceleration due to the driver's accelerator operation (accelerator OFF → ON) is detected, particularly when fuel supply is resumed from the deceleration fuel cut state based on the driver's accelerator operation, Torque control of the engine is performed to prevent torsional vibration.
That is, referring to FIG. 4, when acceleration is performed by the driver's accelerator operation (accelerator OFF → ON) from the deceleration fuel cut state, after the transmission gear backlash (backlash) is packed, the engine output is driven by the vehicle. Although it is transmitted to the shaft, the engine output and the reaction force of the drive system against this act on the drive shaft alternately to generate torsional vibration. That is, after the accelerator is turned OFF → ON, after a loosening period, a torsional vibration period occurs, and in the torsional vibration period, the rate of change in engine speed increases, and a positive value and a negative value are alternately repeated.

Therefore, the engine torque control is performed during the torsional vibration period to suppress the longitudinal vibration of the vehicle (torsional vibration of the drive system).
Such torque control will be described with reference to the flowcharts of FIGS.
FIG. 2 is a flowchart of a torque control flag setting routine. This routine is executed every predetermined time.

In S1, it is determined whether or not the torque control flag F = 1. If F = 0, the process proceeds to S2.
In S2, based on the signal from the accelerator pedal sensor, it is determined whether or not it is immediately after acceleration (accelerator OFF → ON), that is, whether it is within a predetermined time from accelerator OFF → ON.
Note that the acceleration detected here may be detected only when the fuel is recovered by the accelerator operation from the deceleration fuel cut state. This is because the vehicle longitudinal vibration becomes the largest in the case of acceleration from the deceleration fuel cut state.

If it is determined in S2 that the vehicle has just been accelerated, the process proceeds to S3 to determine whether torsional vibration starts. Specifically, a change rate (amount of change within a unit time) ΔNe of the engine speed Ne is detected, and it is determined whether or not this is equal to or greater than a predetermined value SL.
If it is determined in S3 that the torsional vibration is started (ΔNe ≧ SL), the process proceeds to S4, and the torque control flag F is set to 1 to start the torque control.

After the torque control flag F = 1 is set, from the next routine, the process proceeds to S5 by the determination in S1, and the end of torsional vibration is determined. Specifically, it is determined whether or not the engine speed Ne has converged, that is, whether the engine speed change rate ΔNe has converged near zero.
If it is determined in S5 that the torsional vibration has ended, the process proceeds to S6 and the torque control flag F is reset to zero.

FIG. 3 is a flowchart of an air amount and ignition timing control routine. This routine is also executed every predetermined time.
In S11, it is determined whether or not the torque control flag = 1.
When the torque control flag = 0, torque control is not performed. Therefore, the process proceeds to S19, and the air amount increase correction coefficient KQ is set to 1 (no correction) in order to cancel the target air amount increase. In S20, both the ignition timing first correction amount HOS1 and the ignition timing second correction amount HOS2 are set to 0 (no correction) in order to cancel the ignition timing correction.

After these, in S21, the basic target air amount (mainly set based on the accelerator opening) is multiplied by the air amount increase correction coefficient KQ to calculate the final target air amount. Here, KQ = 1 Therefore, the target air amount = the basic target air amount.
In S22, the ignition timing first correction amount HOS1 is subtracted from the basic ignition timing MADV (set based on the engine speed and the load), and the ignition timing second correction amount HOS2 is added to obtain the final value. The ignition timing ADV is calculated. Here, since HOS1 = 0 and HOS2 = 0, the ignition timing ADV = the basic ignition timing MADV.

If it is determined in S11 that the torque control flag F = 1, the process proceeds to S12 in order to perform torque control.
In S12, it is determined whether or not torque control is the first time, and S13 and S14 are executed only in the first time.
In S13, the air amount increase correction coefficient KQ is set to a predetermined value KQ0 (> 1) in order to increase the target air amount. That is, in order to ensure the advance margin of the ignition timing (to enable torque increase by correcting the advance of the ignition timing), it is assumed that the ignition timing is retarded in advance, and torque reduction due to the ignition timing retardation In order to cancel out, the target air amount increase amount (air amount increase correction coefficient KQ) is determined.

In S14, the ignition timing first correction amount HOS1 is set to a predetermined value RET in order to retard the ignition timing so as to cancel the increase in engine torque due to the target air amount increase.
In S15, based on the signal from the crank angle sensor, the engine revolution speed Ne is detected, and the change rate (change amount per unit time) ΔNe of the engine revolution Ne is calculated.
In S16, the engine speed change rate ΔNe is compared with zero.

  As a result of the comparison, when the engine speed change rate ΔNe is negative (ΔNe <0), the process proceeds to S17 to increase the engine torque so as to counteract the force to twist the drive shaft of the vehicle. The ignition timing second correction amount HOS2 is increased with respect to the previous value so that the ignition timing is advanced. Instead of increasing the previous value, the responsiveness may be increased as a predetermined positive value (a constant value or a value proportional to ΔNe).

When the engine speed change rate ΔNe is positive (ΔNe> 0), the process proceeds to S18, and the ignition timing is retarded to reduce the engine torque so as to suppress the force that twists the driving force of the vehicle. Thus, the ignition timing second correction amount HOS2 is decreased from the previous value. Note that the responsiveness may be increased as a negative value determined in advance instead of decreasing the previous value.
After these, in S21, the final target air amount is calculated by multiplying the basic target air amount by the air amount increase correction coefficient KQ as shown in the following equation.

Target air volume = Basic target air volume x KQ
Here, since KQ> 1, the target air amount is corrected to increase with respect to the basic target air amount.
In S22, the final ignition timing ADV is calculated by subtracting the ignition timing first correction amount HOS1 from the basic ignition timing MADV and adding the ignition timing second correction amount HOS2 as shown in the following equation. To do.

ADV = MADV-HOS1 + HOS2
Here, since the first correction amount HOS1> 0, the retard angle correction is uniformly performed by the first correction amount HOS, and the advance timing margin of the ignition timing can be ensured. Then, according to the second correction amount HOS2, according to the change rate ΔNe of the engine speed, when the change rate ΔNe is negative, the ignition timing advance correction is performed. When the change rate ΔNe is positive, the ignition rate is corrected. The timing delay is corrected and the longitudinal vibration of the vehicle (torsional vibration of the drive system) is suppressed.

S18 may be omitted, and the ignition timing control corresponding to the engine speed change rate ΔNe may be only the control for correcting the advance when the engine speed change rate ΔNe in S17 is negative.
FIG. 4 is a time chart for torque control during fuel recovery.
When the accelerator opening APO> 0 is reached by the driver's accelerator operation from the deceleration fuel cut state, the fuel supply is resumed from time t1.

Then, after a loosening period, torsional vibration is started from time t2 and continues until time t3.
During the torsional vibration period, the target air amount is increased and corrected, thereby increasing the throttle opening (and simultaneously increasing the fuel injection amount so that the air-fuel ratio is constant), and ensuring the ignition timing advance margin. Increase torque for Then, by retarding the ignition timing with the ignition timing first correction amount HOS1, the torque increase due to the air amount correction is offset and the advance angle margin is secured.

Then, during the torsional vibration period, according to the change rate ΔNe of the engine speed, when the change rate ΔNe is negative, the ignition timing is advanced by the ignition timing second correction amount HOS2, thereby torsional reaction force The engine torque is increased to counteract the torsional vibration.
Although not shown in FIG. 4, when the rate of change ΔNe of the engine speed Ne is positive, the torsional force is reduced by correcting the ignition timing with the ignition timing second correction amount HOS2. In addition, the engine torque is reduced, which also suppresses torsional vibration.

  As described above, according to the present embodiment, the acceleration state detecting means (S2) for detecting the acceleration state of the vehicle, the rotation speed change rate detecting means (S15) for detecting the change rate of the engine speed, the acceleration An ignition amount increase correction means (S13) for increasing and correcting the intake air amount of the engine so as to increase the engine output for a predetermined period after the detection, and an ignition timing so as to offset the increase of the engine output for the predetermined period. Ignition timing correction means (S14) for delaying the ignition timing, and second ignition timing for correcting the advance of the ignition timing when the rate of change is negative according to the rate of change of the engine speed during the predetermined period. By providing the correction means (S16, S17), the ignition timing can be retarded by an amount corresponding to the increase correction of the intake air amount, and the advance timing margin of the ignition timing can be secured. Changes in engine speed There when negative, by correcting the ignition timing advance, (torsional vibrations in the drive system) longitudinal vibrations of the vehicle can be effectively suppressed.

Further, according to the present embodiment, the second ignition timing correction means corrects the ignition timing when the rate of change is negative according to the rate of change of the engine speed during the predetermined period (S17). When the change rate is positive, the ignition convergence is retarded (S18), so that the vibration convergence can be further improved.
Further, according to the present embodiment, the predetermined period is set to be a generation period of torsional vibration of the vehicle drive system, and is further set excluding a period during which the drive system is loose when accelerating from the deceleration state. As a result, the deterioration of fuel consumption due to the increase in the air amount and the retarded ignition timing can be minimized.

Further, according to the present embodiment, the predetermined period is a period from when acceleration is detected to when the engine speed changes from a predetermined value or more until the engine speed converges. Thus, it is possible to improve the vibration convergence by accurately grasping the torsional vibration period.
Further, according to the present embodiment, there is provided deceleration fuel cut means for stopping fuel supply during a predetermined deceleration operation, and the acceleration state detection means is based on a driver's accelerator operation from a fuel supply stop state by the fuel cut means. By detecting the case where the fuel supply is restarted as acceleration, it is possible to cope with acceleration from a deceleration fuel cut state in which vehicle longitudinal vibration is the most problematic.

  In the above embodiment, the air amount increase correction means is realized by correcting the increase in the throttle opening. However, if the engine has a variable valve timing mechanism, the intake air amount of the engine can be reduced by changing the valve timing. Correction may be performed.

Engine system diagram showing an embodiment of the present invention Torque control flag setting routine flowchart Flow chart of air amount and ignition timing control routine Time chart for torque control during fuel recovery

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Intake passage 3 Electric throttle valve 4 Fuel injection valve 5 Spark plug 6 Transmission 7 Vehicle drive shaft 10 ECU
11 Accelerator pedal sensor 12 Crank angle sensor 13 Air flow meter 14 Vehicle speed sensor

Claims (6)

Acceleration state detecting means for detecting the acceleration state of the vehicle;
Engine speed change rate detecting means for detecting the engine speed change rate;
An air amount increase correction means for increasing and correcting the intake air amount of the engine so as to increase the engine output for a predetermined period after acceleration detection;
First ignition timing correction means for correcting the ignition timing to retard the increase in the engine output during the predetermined period;
Second ignition timing correction means for correcting the advance of the ignition timing when the change rate is negative according to the change rate of the engine speed during the predetermined period;
The control apparatus of the internal combustion engine for vehicles comprised including this.   The second ignition timing correction means corrects the ignition timing when the rate of change is negative according to the rate of change of the engine speed during the predetermined period, and sets the ignition timing when the rate of change is positive. 2. The control apparatus for an internal combustion engine for a vehicle according to claim 1, wherein the retardation is corrected.   2. The control apparatus for an internal combustion engine according to claim 1, wherein the predetermined period is a generation period of torsional vibration of a vehicle drive system.   4. The control apparatus for an internal combustion engine according to claim 3, wherein the predetermined period is set excluding a period during which the drive system is loose when accelerating from the deceleration state.   The predetermined period is a period from when the rate of change of the engine speed becomes equal to or greater than a predetermined value after acceleration detection until the engine speed converges. The control apparatus of the internal combustion engine for vehicles as described in one. A deceleration fuel cut means for stopping fuel supply at a predetermined deceleration operation;
The acceleration state detecting means detects, as acceleration, a case where fuel supply is restarted based on a driver's accelerator operation from a fuel supply stop state by the fuel cut means. Item 6. The control device for an internal combustion engine for a vehicle according to any one of Items 5 to 6.

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