JPH0754696A - Rotational speed controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To suppress excessive decrease in rotational speed by means of sudden closing of an acceleration pedal by making feedback-control by a rotational speed signal with good responsiveness in an internal combustion engine for a vehicle. CONSTITUTION:Signals are inputted from an acceleration sensor 28, an engine rotational speed sensor 27 and electric load and magnitude of decrease in engine rotational speed is judged by an ECU 23 when an acceleration pedal 29 is suddenly closed. Feedback-control (F/B) by a moderated rotational speed signal is performed when the decrease is small. On the other hand, the F/B-control by the rotational speed original signal is performed when the decrease is large. Thereafter, automatic switching is applied to the F/B control by the moderated rotational speed signal. This switching takes place so as to prevent hunting. F/B control and dust pot control by the rotational speed original signal are performed when the decrease is still more large.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to feedback control for making an idle speed of an internal combustion engine a target speed, and more particularly to controlling an excessive drop of the internal combustion engine speed when the accelerator is suddenly closed.

[0002]

2. Description of the Related Art As disclosed in Japanese Patent Laid-Open No. 4-134155, a conventional internal-combustion-engine speed control device is provided with a rotation speed original signal in order to prevent hunting due to a slight fluctuation of the rotation speed original signal. There are those that control the rotation speed by the smoothed rotation speed signal.

[0003]

The smoothed rotation speed signal has a poor response as compared with the rotation speed original signal, and when the accelerator is suddenly closed, the rotation speed original signal falls below the target rotation speed during idling and an undershoot occurs. In contrast, the smoothing speed signal has a period above the target speed. When the idle speed control is executed by the smoothed speed signal in this state, the throttle is closed to try to bring the smoothed speed signal closer to the target speed, which causes a drop in the speed. There was a problem.

In view of the above problems, the present invention makes it possible to properly control the idle speed by using a speed original signal having good response when it is determined that there is a large drop in the speed, such as when the accelerator is suddenly closed. The purpose of this is to suppress an excessive drop in the rotational speed of the internal combustion engine.

[0005]

Means for Solving the Problems To achieve the above object, the means taken by the present invention are a rotation speed drop determining means for determining the magnitude of a drop in the internal combustion engine rotation speed, and a rotation speed of the internal combustion engine. A rotation speed detection means for detecting the number of rotations, a rotation speed original signal output from the rotation speed detection means is smoothed, a smoothed rotation speed calculation means for calculating a smoothed rotation speed signal, and the rotation speed drop determination means are provided. Determined, depending on the size of the rotation speed drop, select the rotation speed original signal or the smoothed rotation speed signal, by the selected rotation speed signal,
Feedback control means for feedback-controlling the internal combustion engine to a target rotation speed, and technical means called an internal combustion engine rotation speed control device.

[0006]

In the present invention as described above, the engine speed drop determining means 1 determines whether the engine speed drop is large or small. On the other hand, the smoothed rotation speed calculation means 4
Calculates a smoothed rotation signal based on the rotation speed original signal output from the rotation speed detection means 3.

Then, the feedback control means 2 selects the rotation speed original signal or the smoothed rotation speed signal according to the determination result of the rotation speed drop determination means 1, and based on the selected rotation speed signal. Feedback control is performed on the rotation speed of the internal combustion engine to the target rotation speed.

[0008]

Therefore, according to the present invention, the feedback control is performed by selecting the rotation speed original signal having a good response or the smoothed rotation speed signal having a small variation depending on whether the decrease in the rotation speed of the internal combustion engine is large or small. By doing so, the respective advantages of the two signals can be utilized. As a result, it is possible to more effectively suppress an excessive drop in the engine speed of the internal combustion engine when the accelerator is suddenly closed.

[0009]

Embodiments of the present invention will be described with reference to the drawings. FIG. 2 is a configuration diagram of this embodiment. The throttle valve 22 adjusts the amount of intake air of the engine 21, and is mechanically connected to the throttle actuator 25.

The throttle sensor 26 is provided on a shaft (not shown) of the throttle valve 22, detects the opening of the throttle valve 22, and sends it to the drive circuit 24 as an electric signal. Further, the throttle valve 22 is provided with an idle switch (idle SW) 30 for accelerator ON / O
The FF signal is sent to the engine control unit (EC
U) 23.

The engine speed sensor 27 is used for the engine 2
1, which is provided on a crankshaft (not shown)
ECU 23 sends a signal for each predetermined crank angle according to the rotation of the
Send to. The accelerator sensor 28 detects the depression amount of the accelerator pedal 29 and sends it to the ECU 23 as an electric signal.

The ECU 23 receives signals such as an accelerator pedal depression amount, an engine speed, an electric load signal, and a gear stage signal (not shown) from sensors of various parts, and controls the throttle valve 22 to an appropriate angle. The value is calculated and sent to the drive circuit 24. In addition, the ECU 2
In No. 3, the rotation speed original signal (NE) is blunted to be used as a parameter for idle speed control / footback (ISCF / B) control, and annealed NE (NESM)
Is constantly calculated. Note that the moderation is arithmetically processed in the ECU 23.

Further, the ECU 23 has a dashpot function. In this embodiment, the dashpot is processed as described later in dashpot control. The drive circuit 24 creates a drive signal by PID control from the throttle command value sent from the ECU 23 and the throttle actual opening signal sent from the throttle sensor 26, and sends it to the throttle actuator 25.

Next, the control contents of this embodiment will be described with reference to FIG.
~ It will be described according to the flowchart of FIG. In the present embodiment, there are roughly four control or arithmetic processings. These are the normal accelerator control shown in FIG. 4, the rotational speed drop determination shown in FIG. 5, the dashpot control shown in FIG. 6, and the ISCF / B control shown in FIGS. 7 and 8.

First, the normal accelerator control shown in FIG. 4 will be described. In step 101, the accelerator depression amount _Acc is detected. In step 102, a normal throttle command value TPDL is calculated from A _cc . Next, FIG.
The determination of the decrease in the number of revolutions will be described. First, in step 201, detects the engine speed Ne, the accelerator depression amount A _cc, and the electrical load signal. In step 202, the accelerator from A _cc detected earlier depression amount change rate △ A
Calculate _cc by the following formula.

[0016]

[Equation 1] In steps 203 to 205, it is determined whether the Ne drop is large or small. In step 203, it is determined whether Ne is in a high rotation state of a predetermined value Ned or more. In step 204, it is determined whether or not the previously calculated ΔA _cc is less than or equal to the predetermined value −ΔAd. Where ΔA _cc
Is less than -ΔAd, it is determined that the accelerator has been suddenly closed. In step 205, the electric load is ON or OF
Judge whether it is F or not.

In steps 203 to 205, Ne becomes N.
When it is determined that it is equal to or less than ed or the accelerator is not closed suddenly, it is determined that the drop in the engine speed is small. At this time, in step 206, the ISCF / B control parameter is set to NESM, and the dashpot filter constant is set to the normal value FILs. Next, at steps 203 to 205, when it is determined that Ne is Ned or more and the accelerator is rapidly closed, it is determined that the drop in the engine speed is large. At this time, in step 207, the ISCF / B control parameter is set to NE, and the dashbot filter constant is set to the normal value FILs.

Finally, in steps 203 to 205,
When Ne is equal to or more than Ned, the accelerator is suddenly closed, and when it is determined that the electric load is ON, it is determined that the drop in the engine speed further increases. At this time, in step 208, the ISCF / B control parameter is set to NE and the dashpot filter constant is set to FILd. The ISCF / B control parameters were set using the flag XISC in this embodiment.
XISC = 0 was set when NESM was set, and XISC = 1 was set when NE was set.

As described above, in the rotation speed drop determination of FIG. 5, the magnitude of the rotation speed drop is determined, and the constants and parameters necessary for the dashpot control and the ISCF / B control are set according to the determination. This processing routine
It is activated by U23 every predetermined time (for example, 0.1 S). Next, the dashpot control shown in FIG. 6 will be described.

First, in step 301, the previous value T of the dashpot opening TDSP calculated by the ECU 23 is calculated.
DSP _n-1 is idle speed control (ISC)
It is determined whether the initial value is KIDLS or more, and TDSP _n-1
If KIDLS, dashboard control execution is permitted. In step 302, the throttle command value TPDL calculated by the normal accelerator control is detected.

In step 303, the detected TPDL is
It is determined whether or not the dashpot start opening KDSP is less than or equal to the dashpot start opening KDSP, and if TPDL KDSP, dashpot control is executed. In step 304, the dashpot opening TDSP is calculated by the following equation.

[0022]

## EQU00002 ## TDSP = (TPDL-TDSP_n-1) ×
Schott filter constant + TDSP_n-1  Note that the dashpot filter constants are
Set in steps 206 to 208 of 5 rpm drop judgment
To be done.

In step 305, the dashpot opening TDSP calculated in step 304 is set to the previous value TDSP.
Remember as _n-1 . Further, the TDSP has a higher priority than the accelerator control etc. after completion of the routine (TDS.
When P> TPDL), it is sent to the drive circuit 24 as a throttle command value. As described above, in the dashpot control of FIG. 6, the dashpot is controlled by the dashpot filter constant set in the rotation speed drop determination of FIG. This processing routine is started by the ECU 23 every predetermined time (for example, 8 mS).

Finally, the ISCF / B control shown in FIGS. 7 and 8 will be described. In steps 401 and 402, I
It is determined whether SCF / B control is possible. Step 40
At 1, it is determined whether or not the dashpot control is completed. When the dashpot opening TDSP is smaller than the preset ISC initial value KIDLS, (TDS
P <KIDLS) It is determined that the dashpot control is completed.

At step 402, the idle SW is turned on.
Or it is determined to be OFF. Steps 401 and 402
Then, when the dashpot control is completed and the idle SW is ON, it is determined that the ISCF / B control is possible. In step 403, the ISCF set in steps 206 to 208 for determining the rotation speed drop in FIG.
The processing is distributed according to the / B parameter.

In steps 404 and 405, in order to control the fall of Ne, feedback control is performed using NE as the ISCF / B parameter. Steps 406, 40
In No. 7, in order to perform normal Ne drop control, feedback control is performed using NESM as the ISCF / B parameter. In step 404, it is determined whether the NE is equal to or less than the ISCF / B start rotation speed KNE.

In step 406, it is determined whether NESM is KNE or less. KN in steps 404 and 406
If it is determined that it is not equal to or less than E, the feedback control is not performed. Note that KNE is obtained from the target rotation speed TNE. In step 405, the difference between TNE and NE is calculated, and in step 407, the difference between TNE and NESM is calculated as ΔNE.

In steps 408 and 409, the feedback control amount ΔTISC of the throttle opening TISC during idling is retrieved from the map according to ΔNE, and is reflected in TISC by the following equation.

[0029]

[Formula 3] TISC = TISC _n-1 + ΔTISC TISC _n-1 : TISC previous value The TISC calculated here has a higher priority than the accelerator control after the routine is completed (TISC> TPD).
L), it is sent to the drive circuit 24 as a throttle command value.

In steps 410 to 414 of FIG.
e In order to suppress the drop, NE set as the ISCF / B parameter is switched to NESM. ISCF
There are the following two conditions for switching the / B parameter. (1) | NE-NESM | ≦ KNER ₁ and | NE-TNE | ≦ KNER ₂ KNER ₁ , KNER ₂ : Predetermined value (2) When ISCF / B control by NE continues for a predetermined time T or more (1 ) Is steps 411 and 412, and (2)
Is determined in step 413.

When either of the conditions (1) and (2) is satisfied, the flag XISC is reset (XISC = 0) in order to switch the ISCF / B parameter in step 414. As described above, I in FIGS.
In the SCF / B control, the ISCF / B control parameter set in the rotation speed drop determination of FIG.
B control is performed. This processing routine is started by the ECU 23 every predetermined time (for example, 0.1 S).

Next, the operation of this embodiment will be described with reference to the time chart of FIG. The time chart of FIG. 3 shows changes in signals of various parts such as the number of revolutions when the accelerator is rapidly returned to the idle region, and is divided into three states up to. First, in the latter half of the section of FIG. 3, when the accelerator is suddenly returned (FIG. 3 (b)), the idle switch is turned from OFF to ON (FIG. 3 (a)), while the throttle is rapidly closed. (FIG. 3D) Next, dashpot control is performed in the section of FIG. The dashpot control (FIG. 6) is executed according to the dashpot filter constant set in the rotation speed drop determination (FIG. 5). The difference in throttle behavior due to the difference in filter constants is shown in the section of FIG. 3 (d). Compared to the case of the solid line in which dashpot control is performed with the normal filter constant FILs, when the control is performed with the filter constant FILd during the Ne drop prevention, the change in the throttle opening becomes gentle as indicated by the alternate long and short dash line. Therefore, the sudden drop of Ne is suppressed.

Next, the ISCF / B control is performed in the section of FIG. The difference in throttle behavior between the prior art and this embodiment is shown in the section of FIG. 3 (d). In the conventional ISCF / B control using the smoothed rotation speed signal shown by the dotted line, since the NESM is equal to or higher than TNE for a long period after the start of the ISC control (FIG. 3 (c)), the throttle opening is extended for a long period.
Moreover, it is controlled to the close side. On the other hand, in the ISCF / B control according to the present embodiment shown by the solid line, Ne
Rapidly decreases, the throttle opening is controlled to the closing side only in the control cycle at the beginning of the ISC control.
Moreover, the amount of control toward the closing side is small, and the fluctuation of the throttle opening is small compared to the conventional one, and it is stable.

By the above-described operation, when the accelerator is suddenly closed, as shown by the solid line in FIG. 3 (d), the drop in the engine speed Ne is greatly reduced as compared with the conventional control shown by the dotted line. In the present embodiment, Ne is calculated from the engine speed at the time of sudden closing of the accelerator and the accelerator depression amount change speed.
Is measured, and when a large dip is predicted, the rotational speed original signal NE having a good response is used as the ISCF / B parameter to suppress the excessive dip of Ne. Furthermore, when a sudden drop in Ne due to an electric load is predicted, the dashpot filter constant is changed to slow the closing speed of the throttle.
It is possible to suppress a sudden drop and also prevent an excessive drop in the engine speed.
That is, a synergistic effect can be obtained by using the dashpot control and the ISCF / B control together.

In the idle stable period, hunting may occur due to minute fluctuations due to NE noise and the like. In order to prevent this, the ISCF / B parameter is changed from the rotation speed original signal NE to the rotation speed signal NESM.
By switching to, the steady-state ISC is stabilized. Although the idle switch is installed on the throttle valve in the first embodiment, it may be installed on the accelerator pedal. Further, even if the idle switch is not provided, it is possible to perform the same detection as that of the idle switch from the depression amount of the accelerator pedal, the throttle opening, and the like.

In the first embodiment, the smoothing signal is calculated by software in the ECU, but it can be calculated by hardware. In the first embodiment described above, the dashpot control is performed by software in the ECU, but the dashpot device may be provided on the throttle valve. Also, with bypass
In a throttle valve in which an ISC valve is provided in the bypass, it is possible to give the ISC valve a dashpot function.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is an overall schematic diagram of an engine and its periphery.

FIG. 3 is a time chart showing changes in signals at various parts when the accelerator is rapidly closed.

FIG. 4 is a flowchart of accelerator control.

FIG. 5 is a flowchart for determining a rotation speed drop.

FIG. 6 is a flowchart of dashpot control.

FIG. 7 is a flowchart of ISCF / B control.

FIG. 8 is a flowchart of ISCF / B control.

[Explanation of symbols]

 21 engine 22 throttle valve 23 engine control unit (ECU) 24 drive circuit 25 throttle actuator 26 throttle sensor 27 engine speed sensor 28 accelerator sensor 29 accelerator pedal 30 idle switch

Claims (1)

[Claims] 1. An engine speed drop determination means for determining the magnitude of a drop in the engine speed, an engine speed detection means for detecting the engine speed of the internal combustion engine, and an engine speed output from the engine speed detection means. The rotation speed original signal or the smoothing rotation speed calculation means for calculating the smoothed rotation speed signal by blunting the original signal, and the rotation speed original signal or not according to the magnitude of the rotation speed decrease determined by the rotation speed decrease determination means. Further, by selecting a rotation speed signal, the internal combustion engine is feedback-controlled to the target rotation speed by the selected rotation speed signal,
An internal combustion engine speed control device comprising: a feedback control means;