JPH0267437A - Air-fuel controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent an engine speed fro being dropped suddenly and to improve the function of an engine brake by increasing a duty value by only a specified value to operation-control an electromagnetic means until deceleration is made and a shift is made to idle operation conditions and the control conditions of idle rotation number is established. CONSTITUTION:A solenoid valve 14 is controlled in its operation according to a duty value from a control unit 16 whereby a bypass passage 12 is opened and closed so that the air amount to a surge tank 8 side from an intake passage 6 is controlled. In this case, when an idle switch 18 is put ON from OFF state, the solenoid valve 14 is operation-controlled for a specified time by means of a duty value increasing by s specified value with respect to steady operation conditions. Until the idling rotation control conditions are established after specified time is elapsed, the solenoid valve 14 is controlled with the duty valve which is larger than specified value with respect to the value of idling state before driving.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an air-fuel ratio control device for an internal combustion engine, and in particular, to a system for preventing a temporary drop in engine speed when decelerating and transitioning to an idling state. The present invention relates to an air-fuel ratio control device for an internal combustion engine that can improve operating performance.

[Conventional technology]

Recently, for internal combustion engines, air-fuel ratio control devices have been proposed that control the air-fuel ratio to obtain the best combustion state in order to reduce fuel consumption rate and harmful exhaust gas components.

An air-fuel ratio control device for an internal combustion engine is provided with a detour passage that bypasses an intake throttle valve provided in an intake passage of the internal combustion engine, and a solenoid valve for ISC (idle rotation speed control), which is an electromagnetic means, is provided in the middle of this detour passage. A control unit is provided as a control means for duty-controlling the solenoid valve by inputting detection signals from a water temperature sensor, an engine rotation speed sensor, a vehicle speed sensor, etc., and the control unit controls the operation of the solenoid valve to pass through the bypass passage. The air-fuel ratio is controlled by increasing or decreasing the amount of air; for example, when the engine speed is increasing, the air amount is decreased, but when the engine speed is decreasing, the air amount is increased and adjusted. There are some that control the rotation speed to a target idle rotation speed.

Further, an apparatus for controlling the amount of fuel supplied to control the air-fuel ratio is disclosed in, for example, Japanese Patent Laid-Open No. 62-240442. The system described in this publication changes the combustion injection pulse time to a predetermined value when the engine speed is less than a predetermined value in an idling operating state to prevent the occurrence of pulsations in the internal combustion engine during an idling operating state. .

Furthermore, a device for controlling the engine speed in an idling state by adjusting the intake air amount of an internal combustion engine is disclosed in, for example, Japanese Patent Application Laid-Open No. 61-277841. In this publication, the throttle valve is fully closed and the engine speed remains higher than the target idle speed and lower than the reference speed between the target idle speed and the predetermined speed for a predetermined period of time. In this case, auxiliary air amount control using feedback mode is started early to lower the engine speed and improve fuel efficiency.

[Problem that the invention seeks to solve]

By the way, in conventional idle speed control, the eighth
As shown in the figure, when driving, the duty value for operating the solenoid valve is fixed at the previous duty value a before starting, and when the car decelerates from the driving state and transitions to the idling state, that is, the idle switch changes from on to off. To prevent the engine speed from rapidly decreasing when the solenoid valve duty value is 100% (indicated by the elapsed time position), the solenoid valve duty value is set at 100% for a predetermined time d from the elapsed time position to the elapsed time position C. The operation is controlled, and the duty value is reduced after a predetermined time d has elapsed (and the predetermined time g is reached from the elapsed time e position to when the idle rotation speed control (ISO) condition takes into account the vehicle speed etc. is satisfied (indicated by the elapsed time r position). The solenoid valve is operated and controlled again using the duty value a before starting.
After the idle speed control is established (after the elapsed time f position), the idle speed control is started.

However, as is clear from FIG. 8, during deceleration, after the solenoid valve is operated and controlled with a duty value of 100%, the duty value is suddenly reduced, and at the elapsed time e position, the duty value a of the idle rotation speed control before starting is changed. Therefore, during the elapsed time period from position C to position e, the engine speed will temporarily drop significantly due to various changes in vehicle operating conditions and internal combustion engine load (indicated by symbol i in Figure 8). There was an inconvenience that the driving performance was degraded due to engine stalling and the like.

Furthermore, if the duty value is set to 100% when the vehicle decelerates and transitions to an idling state, the engine speed during deceleration becomes unnecessarily high, leading to the inconvenience that the effectiveness of engine braking deteriorates depending on the vehicle speed state.

[Purpose of the invention]

Therefore, the purpose of this invention is to eliminate the above-mentioned disadvantages.
The duty value for activating the electromagnetic means when decelerating and transitioning to the idling state is set to be a predetermined value larger than the duty value in the running state, and the duty value for operating the electromagnetic means is set to be a predetermined value larger than the duty value in the running state, and the duty value for operating the electromagnetic means is set to be a predetermined value larger than the duty value in the running state. By controlling the operation of the electromagnetic means by setting the duty value to a predetermined value greater than the duty value in the idling state of the engine, it is possible to prevent the engine speed from dropping suddenly during deceleration, improve driving performance, and improve the effectiveness of engine braking. The object of the present invention is to realize an air-fuel ratio control device for an internal combustion engine that can be improved.

Means for Solving Problem C] In order to achieve this object, the present invention provides a duty control of an electromagnetic means provided in a detour passage that bypasses an intake throttle valve in an internal combustion engine intake passage. In an air-fuel ratio control device for an internal combustion engine that controls the engine speed by increasing or decreasing the amount, the duty value is larger by a predetermined value than the duty value in the running state when decelerating from a running state and transitioning to an idling state. The operation of the electromagnetic means is controlled for a predetermined period of time, and the electromagnetic means is operated at a duty value that is larger by a predetermined value than the duty value in the idle operation state before starting the vehicle until the idle rotation speed control condition is established after the elapse of the predetermined period of time. According to the configuration of the present invention, when decelerating from a running state and transitioning to an idling state, the electromagnetic means is controlled to control the duty value in the running state. The operation is controlled for a predetermined period of time using a duty value that is larger by a predetermined value than , and after the elapse of the predetermined time until the idle speed control condition is established, the duty value is set to be a predetermined value larger than the duty value in the idle operation state before starting. Then, after the idle speed control condition is satisfied, idle speed control is started. As a result, the electromagnetic means operates according to each duty value and opens and closes the detour passage according to the operating condition, so that the appropriate amount of air that matches the operating condition is supplied from this detour passage to the internal combustion engine, and when decelerating. It is possible to avoid a drop in engine speed, prevent engine stalling, etc., improve driving performance, and improve the effectiveness of engine braking.

〔Example〕

Embodiments of the present invention will be described in detail and specifically below based on the drawings.

1 to 7 show an embodiment of the present invention. In FIG. 0, 2 is a vehicle air-fuel ratio control device, 4 is an internal combustion engine,
6 is an intake passage, and 8 is a surge tank. An intake throttle valve 10 is provided in the intake passage 6 to adjust the amount of intake air to the surge tank 8 side. The intake passage 6 on the upstream side of the intake throttle valve 10 and the surge tank 8 on the downstream side of the intake throttle valve 10 are communicated by a bypass passage 12 that is a detour passage that bypasses the intake throttle valve 10. This bypass passage 12
A solenoid valve 14 for ISC (idle rotation speed control), which is an electromagnetic means for duty-controlling the engine rotation speed, is interposed in the middle. This solenoid valve 14
The operation is controlled by a duty value from a control unit 16 serving as a control means, and opens and closes the bypass passage 12 to adjust the amount of air flowing from the intake passage 6 to the surge tank 8 side, thereby controlling the engine speed.

The control unit 16 includes an idle switch 18 that is turned on when the internal combustion engine 4 is idling and turned off when the engine is not idling, a throttle sensor 20 that detects the opening of the intake throttle valve 10, and an engine rotation An engine rotation speed sensor 22 that detects the engine speed, a vehicle speed sensor 24 that detects the vehicle speed, a water temperature sensor 26 that detects the temperature of the cooling water of the internal combustion engine 4, and a buffet battery 28 are in communication with each other.

Furthermore, when the driving state decelerates and transitions to the idle driving state, that is, when the idle switch 18 is turned on from off, the control unit 16 controls the duty value to be larger than the duty value in the traveling driving state by a predetermined value Z%. The operation of the solenoid valve 14 is controlled for a predetermined period of time with a duty value of The operation of the solenoid valve 14 is controlled based on the duty value, and after the idle speed control condition is satisfied, the engine speed is controlled by idle speed control.

Furthermore, when decreasing the duty value after the predetermined time This value is controlled to a small value, thereby gradually lowering the engine speed.

Note that the control unit 16 is configured to prevent the engine speed from dropping when the idling state changes to the time of starting, and when the accelerator switch (not shown) is turned on. In addition, the solenoid valve 14 is controlled to operate at a duty value that is larger by a predetermined value R% than the duty value when the solenoid valve 14 is idle.

Next, the operation of this embodiment will be explained based on the flowchart of FIG. 2.3 and the timing chart of FIGS. 4 to 7.

When the running state changes to the decelerating state, first, the decelerating state is sensed (step 102), and when the idling state changes and the idle switch 18 is turned on in step 104 (the elapsed time H in Fig. 4.5). position), the solenoid pulp 14 is operated and controlled at a duty value B that is larger by a predetermined value Z% than the duty value A in the running state. The operation control of the solenoid pulp 14 at this duty value B is performed for a predetermined time X from the elapsed time H position to the elapsed time 1 position. The predetermined duty value Z% to be added is an arbitrary value, but is such a value that the duty value for operation control is less than 100% so as not to increase the engine speed unnecessarily.

Then, after the predetermined time X has elapsed, that is, after the elapsed time 1 position, the duty value is decreased.

At this time, as shown in FIG. 5.6, when decreasing the duty value, the duty value is slowly decreased by proportional and integral components. That is, as shown in FIG. 3 and the attached table, the control constant is changed depending on the control constant switching rotation speed (CHGN), that is, the value of the engine rotation speed from the engine rotation speed sensor 22. In FIG. 3, when the setting of the control constant starts (step 202), first, compare the control constant switching rotation speed (CHGN) with the engine rotation speed Ne (step 204), and if it is not NekCHGN and the answer in step 204 is NO, , the proportional component Pl and the integral component ■1 are used as control constants (step 206), while Ne≧
If step 204 is YES in CHGN, use proportional component P2 and integral component ■2 as control constants in step 208.
), and end 210.

In Fig. 2, idle speed control (ISO
) If the condition is not satisfied and step 108 is NO, then
At the elapsed time J position after a predetermined time has elapsed from the elapsed time 1 position, the solenoid valve 14 is actuated and controlled according to a duty value obtained by adding a predetermined value Y% to the duty value C in the idling state before starting (step 110), and Return to step 208. In this embodiment, the duty value A in the running state and the duty value before the idle speed control condition is satisfied during deceleration are defined as
It is. This predetermined value Y% is an arbitrary set value, but it is preferable that the duty value is around the duty value A.

That is, during a predetermined time K from the elapsed time position 1 to the elapsed time position J, the control constant is changed according to the engine speed as described above, the duty value is changed slowly as indicated by the diagonal line p1, and the engine speed is suddenly decreased. to prevent

On the other hand, after a predetermined period of time has elapsed since the elapsed time J, is the number of idle revolutions determined? If the I (ISC) condition is satisfied at the elapsed time M and YES in step 108, the idle rotation speed control is started (step 112) and then ended (step 114).

Similarly, when decreasing the duty value from the elapsed time M position, the duty value is slowly changed as indicated by the diagonal line P2 from the elapsed time M position to the elapsed time N position.

After the elapsed time N position, the solenoid valve 14 is operated and controlled at the normal duty value E without changing the control constant.

Attached Table As a result, when reducing the duty value from duty value B, the engine speed is gradually lowered and the duty value is temporarily reduced to D before the idle speed control condition is satisfied.
By holding the engine speed at i, the engine speed does not suddenly drop as in the conventional case, and it is possible to prevent engine stalling and the like, thereby improving driving performance.

Furthermore, since the engine speed is gradually lowered, the effectiveness of engine braking can be improved.

As shown in FIG. 7, the control unit 16 in this embodiment adds a predetermined value R% to the duty value Q during idling when the accelerator switch is turned on when transitioning from the idling state to the time of starting. The operation of the solenoid valve 14 is controlled by the duty value S, which is set to a duty value S that is larger than the conventional duty value m by R%, and the engine rotational speed is reduced during the transition from idling to starting. (indicated by symbol n in FIG. 7) and increases the engine speed as indicated by symbol T in FIG. 7,
Driving performance when starting can be improved.

[Effects of the Invention] As is clear from the above detailed description, according to the present invention,
The duty value for activating the electromagnetic means when the vehicle decelerates and transitions to the idling state is set to be a predetermined value larger than the duty value in the running state, and the vehicle starts running until the idle speed control condition is met after a predetermined period of time has elapsed. By controlling the operation of the electromagnetic means by setting the duty value to be a predetermined value larger than the duty value in the previous idling state, it is possible to prevent the engine speed from dropping suddenly during deceleration, improve driving performance, and improve the effectiveness of engine braking. can be considered good.

[Brief explanation of the drawing]

1 to 7 show an embodiment of the present invention, in which FIG. 1 is an air-fuel ratio control device, FIG. 2 is a flowchart explaining the operation of this embodiment, FIG. 3 is a flowchart for determining control constants, and FIG. The figure is a timing chart of duty value, engine rotation speed, and elapsed time. Figure 5 is a timing chart of duty value and elapsed time from running state to deceleration operation state. Figure 6 is a timing chart of engine revolution number and elapsed time. FIG. 7 is a timing chart of the duty value and elapsed time from idling to starting. FIG. 8 is a conventional timing chart during deceleration. In the figure, 2 is an air-fuel ratio control device, 4 is an internal combustion engine, 6 is an intake passage, 8 is a surge tank, IO is an intake throttle valve, 12
14 is a bypass passage, 14 is a solenoid pulp, 16 is a control unit, 18 is an idle switch, 20 is a throttle sensor, 22 is an engine speed sensor, 24 is a vehicle speed sensor, 2
6 is a water temperature sensor, and 28 is a battery.

Claims (1)

[Claims] 1. In an air-fuel ratio control device for an internal combustion engine that controls the engine speed by increasing or decreasing the amount of air passing through the electromagnetic means by controlling the duty of an electromagnetic means provided in a bypass passage that bypasses an intake throttle valve in an intake passage of the internal combustion engine. , the electromagnetic means is controlled to operate for a predetermined period of time at a duty value that is larger than the duty value in the running state by a predetermined value when decelerating from a running state to an idling state; An air-fuel ratio of an internal combustion engine, characterized in that a control means is provided for controlling the operation of the electromagnetic means at a duty value that is larger by a predetermined value than a duty value in an idling state before starting until a rotation speed control condition is satisfied. Control device.