JP4345063B2 - Dashpot control device for internal combustion engine - Google Patents

Description

  The present invention relates to a dashpot control device for an internal combustion engine having a function of preventing a sudden decrease in actual rotational speed when switching to idle operation during deceleration operation of the internal combustion engine.

  In an internal combustion engine mounted on a vehicle, especially when switching to idle operation during deceleration operation by accelerator off (idle switch on) from a high rotation state, when the throttle opening (throttle valve opening) is suddenly reduced, There is a possibility that the actual rotation speed will drop sharply and drivability will be adversely affected.

As a countermeasure, for example, as described in Patent Document 1 (Japanese Patent Application Laid-Open No. 56-96124), when switching to idle operation during deceleration operation, the throttle opening is gradually decreased to reduce the actual rotational speed. Is gradually reduced to the idle rotation speed.
JP 56-96124 A (6th page, FIG. 4 etc.)

  Further, as shown in the upper part of FIG. 5, the inventors set the target idle rotation speed TNid to the actual rotation speed Ne when the actual rotation speed Ne is lower than a predetermined dashpot upper limit value Ndp during acceleration operation. Thus, when the actual rotational speed Ne is equal to or higher than the dashpot upper limit value Ndp, the target idle rotational speed TNid is set to the dashpot upper limit value Ndp. We are researching a system that executes dashpot control that gradually attenuates to the idling speed Nid. In this system, when the idle rotation speed control (the control for converging the actual rotation speed Ne to the target idle rotation speed TNid) is started during the deceleration operation from the high rotation state, the actual rotation speed Ne is rapidly decreased by the dashpot control. Can be prevented.

  However, in the above system, as shown in the lower part of FIG. 5, a slight drop in rotation during acceleration operation such as during chip in-racing (short time and relatively large accelerator depression) is determined as deceleration operation, and acceleration operation is performed. Dashpot control may be started accidentally. In such a case, when switching to idle operation during subsequent deceleration operation, the target idle rotation speed TNid has already been attenuated to near the normal idle rotation speed Nid by dashpot control that was erroneously started during the previous acceleration operation. Therefore, the normal dashpot control cannot be executed, and the actual rotational speed Ne may be rapidly reduced.

  The present invention has been made in view of such circumstances. Accordingly, the object of the present invention is to switch to idle operation during subsequent deceleration operation even if dashpot control is erroneously started during acceleration operation. Another object of the present invention is to provide a dashpot control device for an internal combustion engine that can execute dashpot control as usual and prevent a sudden decrease in the actual rotational speed.

In order to achieve the above object, in the dashpot control device for an internal combustion engine according to claim 1 of the present invention, the dashpot control preparation means performs the dashpot control with the actual rotational speed during non-idle operation of the internal combustion engine. The target idle rotation speed is set to the actual rotation speed when it is lower than the dashpot upper limit value that is the upper limit value of the rotation speed range, and the target idle rotation speed is set to the dashpot upper limit value when the actual rotation speed is equal to or higher than the dashpot upper limit value. Set and execute dashpot control that gradually attenuates the target idle speed set by the dashpot control preparation means to the normal idle speed when switching to idle operation during deceleration operation of the internal combustion engine by the dashpot control means The dashpot control stop means Actual rotational speed during Yupotto control is obtained so as to raise the target idle rotation speed to cancel the dashpot control when it is above a predetermined stop judgment value dashpot upper limit.

  In this configuration, even if a slight drop in rotation during acceleration operation is determined as deceleration operation, and the dashpot control is erroneously started during acceleration operation, the actual rotation speed exceeds the stop determination value during the dashpot control. When it is determined that the vehicle is not decelerating, the dashpot control can be stopped and the target idle rotation speed can be raised to the dashpot upper limit value. As a result, when switching to idle operation during subsequent deceleration operation, the normal dashpot control can be executed with almost no influence of the dashpot control that was erroneously started during the previous acceleration operation, A sudden decrease in the actual rotation speed can be prevented.

  By the way, the dashpot control started at the time of deceleration operation from the high rotation state gradually attenuates the target idle rotation speed from the dashpot upper limit value to the normal idle rotation speed. If the actual rotation speed is set to a dashpot upper limit value or a value lower than that, the actual rotation speed is determined to be higher than the stop determination value during dashpot control started during deceleration operation, and the dash started during deceleration operation is determined. Pot control may be canceled.

  As a countermeasure, it is preferable to set the stop determination value (actual rotational speed at which the dashpot control is stopped) to a value higher than the dashpot upper limit value as in claim 2. In this way, it is possible to prevent the dashpot control started during the deceleration operation from being canceled because the actual rotational speed is determined to be equal to or higher than the stop determination value during the dashpot control started during the deceleration operation. it can.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
First, a schematic configuration of the entire engine control system will be described with reference to FIG. An air cleaner 13 is provided at the most upstream portion of the intake pipe 12 of the engine 11 that is an internal combustion engine, and an air flow meter 14 that detects the intake air amount is provided downstream of the air cleaner 13. A throttle valve 16 whose opening is adjusted by a motor 15 and a throttle opening sensor 17 that detects the opening (throttle opening) of the throttle valve 16 are provided on the downstream side of the air flow meter 14.

  Further, a surge tank 18 is provided on the downstream side of the throttle valve 16, and an intake pipe pressure sensor 19 for detecting the intake pipe pressure is provided in the surge tank 18. The surge tank 18 is provided with an intake manifold 20 for introducing air into each cylinder of the engine 11, and a fuel injection valve 21 for injecting fuel is attached in the vicinity of the intake port of the intake manifold 20 of each cylinder. Yes. An ignition plug 22 is attached to the cylinder head of the engine 11 for each cylinder, and the air-fuel mixture in the cylinder is ignited by spark discharge of each ignition plug 22.

  On the other hand, the exhaust pipe 23 of the engine 11 is provided with an exhaust gas sensor 24 (air-fuel ratio sensor, oxygen sensor, etc.) for detecting the air-fuel ratio or rich / lean of the exhaust gas. A catalyst 25 such as a three-way catalyst for purifying gas is provided.

  A cooling water temperature sensor 26 that detects the cooling water temperature and a crank angle sensor 27 that outputs a pulse signal each time the crankshaft of the engine 11 rotates a predetermined crank angle are attached to the cylinder block of the engine 11. Based on the output signal of the crank angle sensor 27, the crank angle and the engine speed are detected.

  Outputs of these various sensors are input to an engine control circuit (hereinafter referred to as “ECU”) 28. The ECU 28 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium), so that the fuel injection amount of the fuel injection valve 21 can be changed according to the engine operating state. The ignition timing of the spark plug 22 is controlled. At this time, the ECU 28 performs idle rotation speed control that feedback-controls the throttle opening so that the actual rotation speed Ne of the engine 11 coincides with the target idle rotation speed TNid when the idle switch is turned on due to the accelerator off or the like. Execute.

Further, the ECU 28 executes the following control by executing a target idle speed setting program shown in FIG. 2 and a dashpot control program shown in FIG.
As shown in the upper part of FIG. 4, when the actual rotation speed Ne of the engine 11 is lower than a predetermined dashpot upper limit value Ndp (for example, 1500 rpm) during acceleration operation, the target idle rotation speed TNid is set to the actual rotation speed Ne. When the actual rotation speed Ne is equal to or higher than the dashpot upper limit value Ndp, the target idle rotation speed TNid is set to the dashpot upper limit value Ndp.

  When switching to idle operation during subsequent deceleration operation, when a predetermined dashpot control execution condition is satisfied, the dashpot control execution flag is set to ON and the target idle rotation speed TNid is set to the normal idle rotation speed Nid. Dashpot control that gradually attenuates to (for example, 500 rpm) is executed. As a result, when the idle rotation speed control is started during the deceleration operation from the high rotation state, the sudden decrease in the actual rotation speed Ne is prevented by the dashpot control.

  In addition, as shown in the lower part of FIG. 4, it is determined that a slight rotation drop during acceleration operation such as during chip in-racing (short-time and relatively large accelerator depression) is a deceleration operation, and erroneously occurs during acceleration operation. There is a possibility that the dashpot control will be started, but in this embodiment, during the dashpot control, the actual rotational speed Ne exceeds a predetermined stop determination value Nx (for example, a value slightly higher than the dashpot upper limit value Ndp). At this time, it is determined that the vehicle is not decelerating, the dashpot control execution flag is reset to OFF, the dashpot control is stopped, and the target idle rotation speed TNid is raised to the dashpot upper limit value Ndp. As a result, even if the dashpot control is mistakenly started during the acceleration operation, when switching to the idle operation during the subsequent deceleration operation, the dashpot control that was erroneously started during the previous acceleration operation is not affected at all. In addition, the normal dashpot control is executed to prevent the actual rotational speed Ne from rapidly decreasing.

  Hereinafter, the processing contents of the target idle speed setting program of FIG. 2 and the dashpot control program of FIG. 3 executed by the ECU 27 will be described.

[Target idle speed setting]
The target idle speed setting program shown in FIG. 2 is executed at a predetermined cycle during engine operation. When this program is started, first, in step 101, it is determined whether or not the dashpot control execution flag is turned on. As a result, when it is determined that the dashpot control execution flag is turned on, the routine proceeds to step 109, where the target idle rotation speed TNid is gradually attenuated to the normal idle rotation speed Nid (for example, 500 rpm) by the attenuation coefficient. Execute dashpot control.

  On the other hand, if it is determined in step 101 that the dashpot control execution flag is turned off, the process proceeds to step 102 to determine whether the idle switch is turned on, for example, whether the accelerator is turned off. Determine by. As a result, if it is determined that the idle switch is turned on, the routine proceeds to step 103, where it is determined whether or not the actual rotational speed Ne is lower than a dashpot upper limit value Ndp (for example, 1500 rpm).

  If it is determined in step 103 that the actual rotational speed Ne is lower than the dashpot upper limit value Ndp, the routine proceeds to step 104, where the target idle rotational speed TNid is set to a normal idle rotational speed Nid (for example, 500 rpm). . On the other hand, if it is determined in step 103 that the actual rotational speed Ne is equal to or higher than the dashpot upper limit value Ndp, the routine proceeds to step 105, where the target idle rotational speed TNid is set to the dashpot upper limit value Ndp.

  On the other hand, if it is determined in step 102 that the idle switch is turned off, it is determined that the engine is in non-idle operation such as acceleration operation, and the process proceeds to step 106 where the actual rotational speed Ne is determined. Is lower than the dashpot upper limit value Ndp.

If it is determined in step 106 that the actual rotational speed Ne is lower than the dashpot upper limit value Ndp, the routine proceeds to step 107, where the target idle rotational speed TNid is set to the actual rotational speed Ne. On the other hand, if it is determined in step 106 that the actual rotational speed Ne is equal to or higher than the dashpot upper limit value Ndp, the routine proceeds to step 108, where the target idle rotational speed TNid is set to the dashpot upper limit value Ndp.
The processing of these steps 106 to 108 serves as dashpot control preparation means in the claims.

[Dashpot control]
The dashpot control program shown in FIG. 3 is executed at a predetermined cycle during engine operation, and serves as a dashpot control means in the claims. When this program is started, first, in step 201, it is determined whether or not the dashpot control execution flag is turned on.

As a result, when it is determined that the dashpot control execution flag is turned off, the process proceeds to step 202 to determine whether or not the dashpot control execution condition is satisfied. Here, the dashpot control execution condition is to satisfy all of the following conditions (1) to (4), for example.
(1) The idle switch is turned on
(2) The fuel is not being cut
(3) The difference between the actual rotational speed Ne and the target idle rotational speed TNid is not more than a predetermined threshold value.
(4) During deceleration operation [current actual rotational speed Ne (i) <previous actual rotational speed Ne (i-1)]

If all of the above conditions (1) to (4) are met, the dashpot control execution condition is satisfied. The pot control execution condition is not satisfied.
If it is determined in step 202 that the dashpot control execution condition is not satisfied, the program is terminated while the dashpot control execution flag is kept off.

  On the other hand, if it is determined in step 202 that the dashpot control execution condition is satisfied, the process proceeds to step 203, and the dashpot control execution flag is set to ON. Thereby, the dash pot control is executed to gradually attenuate the target idle rotation speed TNid to the normal idle rotation speed Nid.

  During execution of the dashpot control, it is determined in step 201 that the dashpot control execution flag is turned on, and the process proceeds to step 204 where the actual rotational speed Ne is set to the stop determination value Nx (for example, the dashpot upper limit value Ndp). It is determined whether or not the value is a little higher than that).

If it is determined in step 204 that the actual rotational speed Ne is equal to or higher than the stop determination value Nx, it is determined that the vehicle is not decelerating, and the process proceeds to step 205 where the dashpot control execution flag is reset to OFF. After stopping the pot control, the routine proceeds to step 206 where the target idle rotation speed TNid is raised to the dashpot upper limit value Ndp.
The processing of these steps 204 to 206 serves as dashpot control stopping means in the claims.

  On the other hand, if it is determined in step 204 that the actual rotational speed Ne is lower than the stop determination value Nx, the process proceeds to step 207 where the target idle rotational speed TNid is set to the normal idle rotational speed Nid by dashpot control. It is determined whether or not it has decreased.

  If it is determined in step 207 that the target idle rotation speed TNid is higher than the normal idle rotation speed Nid, the dashpot control execution flag is kept on and the dashpot control is continued.

  Thereafter, when it is determined in step 207 that the target idle rotation speed TNid has decreased to the normal idle rotation speed Nid, the routine proceeds to step 208, where the dashpot control execution flag is reset to OFF and the dashpot control is terminated. .

  In the present embodiment described above, as shown in the lower part of FIG. 4, it is determined that a slight rotational drop during acceleration operation such as during chip in-racing (short-time and relatively large accelerator depression) is a deceleration operation, Even if the dashpot control is mistakenly started during acceleration operation, when the actual rotational speed Ne exceeds the stop determination value Nx during the dashpot control, it is determined that the vehicle is not decelerating and the dashpot control is performed. It can be stopped and the target idle speed TNid can be raised to the dashpot upper limit value Ndp. As a result, even if the dashpot control is mistakenly started during the acceleration operation, when switching to the idle operation during the subsequent deceleration operation, the dashpot control that was erroneously started during the previous acceleration operation is not affected at all. In addition, the normal dashpot control can be executed, and a sudden decrease in the actual rotation speed can be prevented.

  By the way, as shown in FIG. 4, the dashpot control started during the deceleration operation from the high rotation state is stopped because the target idle rotation speed TNid is gradually attenuated from the dashpot upper limit value Ndp to the normal idle rotation speed Nid. If the judgment value Nx (actual rotational speed at which the dashpot control is stopped) is set to a dashpot upper limit value Ndp or a value lower than that, the actual rotational speed Ne is set to the stop judgment value Nx during the dashpot control started during deceleration operation. As a result, the dashpot control started during the deceleration operation may be stopped.

  In this respect, in this embodiment, the stop determination value Nx (actual rotational speed at which the dashpot control is stopped) is set to a value higher than the dashpot upper limit value Ndp, so that the dashpot started during the deceleration operation is set. During the control, it is possible to prevent a problem that the actual rotational speed Ne is determined to be equal to or higher than the stop determination value Nx and the dashpot control started during the deceleration operation is stopped.

  In the above-described embodiment, the present invention is applied to a system that controls the idle rotation speed by the throttle valve 16, but the present invention is applied to a system that controls the idle rotation speed by an idle speed control valve provided separately from the throttle valve 16. It may be applied.

It is a schematic block diagram of the whole engine control system in one Example of this invention. It is a flowchart which shows the flow of a process of a target idle rotational speed setting program. It is a flowchart which shows the flow of a process of a dashpot control program. It is a time chart which shows the execution example of the dashpot control of a present Example. It is a time chart which shows the execution example of the dashpot control of a comparative example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 16 ... Throttle valve, 21 ... Fuel injection valve, 22 ... Spark plug, 23 ... Exhaust pipe, 28 ... ECU (Dashpot control preparation means, dashpot control means, dash Pot control stop means)

Claims (2)

In a dashpot control device for an internal combustion engine having a function of executing dashpot control that gradually attenuates a target idle rotation speed,
When the actual rotational speed is lower than the dashpot upper limit value that is the upper limit value of the rotational speed range in which the dashpot control is executed during non-idle operation of the internal combustion engine, the target idle rotational speed is set to the actual rotational speed, and the actual rotational speed is set. Dashpot control preparation means for setting the target idle rotation speed to the dashpot upper limit value when the speed is equal to or higher than the dashpot upper limit value;
Dashpot control means for executing dashpot control that gradually attenuates the target idle rotation speed set by the dashpot control preparation means to the normal idle rotation speed when switching to idle operation during deceleration operation of the internal combustion engine;
Dashpot control stopping means for stopping the dashpot control and raising the target idle rotation speed to the dashpot upper limit value when the actual rotation speed exceeds a predetermined stop determination value during the dashpot control. A dashpot control device for an internal combustion engine, comprising:   The dashpot control device for an internal combustion engine, wherein the stop determination value is set to a value higher than the dashpot upper limit value.

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