JPS63268949A - Idling speed control device for engine - Google Patents

Abstract

PURPOSE:To enable a smooth rotational frequency change free from a sharp decrease in the engine speed to be provided by diminishing the controlled variable for damping in the case where the difference between an actual engine speed and a desired engine speed is decreased to less than a prescribed value in a damping control subsequent to an intake increasing control. CONSTITUTION:A control unit 16 judges from various signals whether the operating range of an engine 1 falls within a starting zone, and then, if said range falls within the starting zone, it presets the initial value of a starting intake quantity correction value. And further, after starting, a prescribed period of time elapses until said range is out of the starting zone, it makes correction for an increase of the starting intake quantity through controlling an intake control valve 13 for adjusting the quantity of flow in a by-pass passage 12. After said range passes beyond the starting zone, it decreases the starting intake quantity correction value gradually. Hereupon, although the damping amplitude is set to be large in the comparatively initial stages, if the difference between an actual engine speed and a desired engine speed is decreased to less than a prescribed value, the damping amplitude is made smaller. Thereby, the feedback control cannot be adversely affected, and accordingly, a marked falling off in the engine speed can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine idle speed control device,
In particular, it relates to an idle rotation speed control device that performs rotation speed feedback control during idle operation, performs intake air increase control during specific operations such as startup, and attenuates this intake air increase control after a predetermined period of time has elapsed.

(Prior Art) In order to ensure good convergence to a target idle rotation speed in idle rotation speed control, an idle rotation speed control device that performs feedback control of the idle rotation speed is known.

For example, Japanese Patent Application Laid-Open No. 54-98413 discloses an engine that performs such idle rotation speed feedback control, and this disclosed device has an auxiliary air passage that bypasses the throttle valve to control the idle speed during idle operation. The throttle valve is fully closed and intake air is introduced from the auxiliary air passage. A control valve provided in the auxiliary air passage adjusts the amount of intake air to converge the idle rotation speed to the target rotation speed.

Further, in this disclosed device, in order to obtain a smooth increase in the rotational speed when starting the engine, the amount of intake air introduced through the auxiliary air passage is increased for a predetermined period at the time of starting.

(Problem to be solved) When increasing the amount of fuel for a certain period of time at startup as described above, the intake air amount is reduced after the rotational speed reaches a predetermined value and the desired purpose is achieved by revving up. The idle feedback control will be started while the engine is running. However, in the device disclosed in Japanese Patent Application Laid-Open No. 54-98413, when the fuel increase control is performed at the time of starting, and then the idle speed feedback control is performed while attenuating the fuel increase control, the damping control is When the control amount is large, the controllability of feedback control deteriorates, causing a problem that the rotational speed temporarily drops.

(Means for solving the problems) The present invention is configured to solve the above problems,
In an engine in which intake increase control is performed and the increase correction is attenuated after a predetermined period of time has elapsed, when idle rotation speed feedback control is performed while performing attenuation control of the increase correction, a drop in rotation speed may occur. It is an object of the present invention to provide an idle rotation speed control device that can give smooth rotation speed changes without any problems.

The control device according to the present invention is a control device for an engine equipped with a mechanism that performs feedback control of the idle rotation speed, and a mechanism that controls the intake air amount to increase in a specific engine operating range and attenuates the intake air amount increase control amount as time passes. The idle rotation speed control device is configured to reduce an intake damping control amount when the difference between the engine rotation speed and the target rotation speed becomes a predetermined value or less in the damping control after the intake air increase control. It is characterized by:

According to the present invention, when the intake air amount increase control is performed during a specific engine operation, when the intake air amount is attenuated after the desired engine speed is obtained, the actual engine speed and the target idle speed are When the difference becomes less than a predetermined value, feedback control is performed by reducing the attenuation period.

(Effects of the Invention) According to the present invention, by controlling as described above, there is no influence of temporary intake increase control, that is,
Attenuation control and feedback control for fuel increase correction can be performed smoothly without causing a temporary drop in engine speed.

(Description of Embodiment) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

Referring to FIG. 1, a piston 2 is slidably housed inside the engine 1 of this example, and a space above the piston 2 constitutes a combustion chamber 3. An intake passage 4 and an exhaust passage 5 communicate with this combustion chamber 3, and an intake valve 6 and an exhaust valve 7 are associated with respective boats of each passage 4.5.

A spark plug 3a faces the combustion chamber 3.-6 An air cleaner 8 is attached to the upstream end of the intake passage 4, and an air flow sensor 9 is disposed downstream thereof.

A throttle valve IO is downstream of the air flow sensor 9.
A throttle opening sensor 10a for detecting the opening of the throttle valve IO is attached to the throttle valve IO.

A surge tank 4a is formed in the intake passage downstream of the throttle valve IO, and an injector 11 for injecting fuel is installed near the combustion chamber 3 further downstream.

Furthermore, a bypass passage 12 is provided in the intake passage 4 so as to bypass the throttle valve 10, that is, to allow a predetermined amount of air to flow even when the throttle valve 10 is fully closed. The bypass passage 12 is provided with an intake control valve 13 that adjusts the flow rate.

Further, the engine 1 of this example has a distributor 14 that rotates in synchronization with the crankshaft, and a crank angle sensor 15 is attached to the distributor 14.

Further, the engine 1 of this example preferably includes a microcomputer that outputs a signal for controlling fuel injection to the injector 11 and a control signal for adjusting the opening degree of the intake control valve 13 of the bypass passage 12. A control unit throat 16 is provided.

The control unit 16 receives a signal representing the intake air amount from the air flow sensor 9, a signal representing the opening degree of the throttle valve 10, a signal from the water temperature sensor 17, a signal from the atmospheric temperature sensor 18, a crank angle sensor 15, etc. signal is input.

Next, idle rotation speed control according to an embodiment of the present invention will be described with reference to FIGS. 2 and 3.

First, in FIG. 2, the control unit throat 16 reads various data for calculating the operating state, such as the engine rotational speed (Ne) and the intake air amount (Sl).

Next, the control unit 7t/16 determines whether the operating region is in the starting zone based on the above-mentioned various No. 43 (S2) If it is in the starting zone, sets the initial value of the starting intake air increase correction value G- (S3) .

As shown in FIG. 3(a), the engine rotation speed (Ne) is kept at a predetermined target rotation speed (No. The starting intake air amount increase correction is performed until the actual engine speed (Ne) reaches the target speed (NO) after the predetermined time TI has elapsed, that is, after the engine has left the starting zone. Intake increase correction value G
- Gradually decrease.

In this case, at a relatively early stage, a middle damping point with a large starting intake air increase correction value Gw is set.

Then, after a predetermined period of time has elapsed, the attenuating period is reduced.

That is, the control unit 16 performs the step (S
In 2), if the engine moves out of the starting zone, it is determined whether or not it is in an idling operating state.S4) If it is in an idling operating state, the engine speed (Ne) and the target engine speed (No) are compared. (S5), actual rotation speed (N
e) and the target rotational speed (NO) is equal to or greater than the predetermined value, the above-mentioned large damping mode D1 is set (S6
), if it becomes less than the predetermined value A, in this example, the time T
2, a relatively small attenuation D2 of the starting intake air increase correction value G- is set (S7).

Furthermore, the control unit 16 operates so that the correction value Gw does not become negative through this damping control (S8, S9), and also adjusts various correction intake air amounts B such as the control amount in the idle rotation speed feedback control. In addition, the total intake correction amount Ga is determined (SIO).

Then, the fuel injection duty ratio is calculated by multiplying this total amount Ga by a predetermined coefficient (Sll).

According to the above control of this example, when the damping control of the starting intake air increase correction and the idle speed feed pack control are performed in parallel, the engine speed (Ne) approaches the target speed (No). In such an operating state, the control amount of the damping control is reduced, so that the feedback control is not adversely affected, and therefore the drop in the rotational speed can be eliminated.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram of an engine that can be equipped with the idle speed control device according to the present invention, Fig. 2 is a flowchart showing the control contents, and Fig. 3 is a graph showing changes in rotation speed and control amount over time. This is a graph that hails change. 1... Engine, 2... Piston, 3... Combustion chamber, 4... Intake passage, 5... Exhaust passage, 6. ...Intake valve, 7...Exhaust valve, 8...
Air cleaner, 9... Air flow sensor, 10... Throttle valve, 11... Injector, 12... Bypass passage, 13... Intake control Valve, 16... Control unit.

Claims (1)

[Claims] An engine idle speed control device comprising a mechanism that performs feedback control of the idle speed, and a mechanism that controls an increase in intake air amount in a specific engine operating range and attenuates the intake air increase control amount as time passes. ,
An engine idle characterized in that the intake air damping control amount is reduced when the difference between the engine rotation speed and the target rotation speed becomes equal to or less than a predetermined value in the damping control after the intake air increase control. Rotation speed control device.