JP2785590B2 - Air flow control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for controlling an intake air amount of an internal combustion engine.

[0002]

2. Description of the Related Art Generally, in order to improve exhaust emissions of an internal combustion engine, a three-way catalyst is installed in an exhaust system, and H
It is known that the oxidation of C and CO and the reduction of NO are performed at the same time. However, such a catalyst can maintain the initial exhaust gas purification efficiency only in an active state at a predetermined temperature or higher. For this reason, exhaust emissions increase until the catalyst temperature rises, such as during a cold start of the engine.If the engine cooling water temperature is low, the exhaust temperature is raised by retarding the ignition timing to increase the exhaust temperature. It is trying to recover the function of the catalyst early.

[0003] If the ignition timing is retarded for warming up the catalyst, the combustion efficiency deteriorates, and the rotational speed tends to fluctuate unstablely during idling operation. Corrections have been made (e.g.,
JP-B-61-33983, see).

[0004]

However, such a conventional apparatus is provided with an idle control valve (auxiliary air valve) for adjusting the amount of auxiliary air guided around the throttle valve, and is provided with an idle speed. If the idle control valve or its control system fails, the intake air amount becomes insufficient during the ignition timing retard control during the warm-up, or the intake air amount Could increase unnecessarily.

An object of the present invention is to address the above problems and to solve them.

[0006]

SUMMARY OF THE INVENTION The present invention relates to an internal combustion engine for performing ignition timing retard control required for activation of a catalyst in a cold state, and a first bypass passage for guiding intake air bypassing an intake throttle valve. The two bypass passages are arranged in parallel, and the first bypass passage is provided with an idle control valve for adjusting the intake air amount so as to feedback-control the idle speed, while the second bypass passage is provided with an electromagnetic on-off valve. A control device is provided for opening the electromagnetic on / off valve in conjunction with the ignition timing retard control, and a rotation for closing the electromagnetic on / off valve in response to the engine speed rising to a predetermined value or more. Provide a switch.

[0007]

The control device opens the electromagnetic on-off valve at the time of warm-up in which ignition timing retard control is performed, thereby preventing a decrease in engine torque.

When the engine speed rises above a predetermined value, the rotary switch shuts off the drive current sent from the control device to the solenoid on-off valve, and forcibly closes the solenoid on-off valve. Even if the control device of the electromagnetic on-off valve fails, the electromagnetic on-off valve does not remain open, and an increase in the intake air amount can be suppressed.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, 1 is an engine body, 2 is an intake passage, 3 is an exhaust passage, 4 is an intake valve, and 5 is an exhaust valve. A three-way catalyst 6 is provided in the exhaust passage 3 so that HC, C
O is oxidized and NO is reduced.

Reference numeral 7 denotes a fuel injection valve for injecting fuel into the intake passage 2, and reference numeral 8 denotes an ignition plug for igniting an air-fuel mixture in a combustion chamber 9.

A control device 11 is provided for controlling the amount of fuel injected from the fuel injection valve 7 and for controlling the ignition timing of an ignition device 10 for igniting the ignition plug 8.

The control device 11 controls the amount of intake air detected by the air flow sensor 12 so that the fuel injected from the fuel injection valve 7 has the stoichiometric air-fuel ratio in order to maintain the conversion efficiency of the three-way catalyst 6 to the maximum. Then, the fuel injection amount is calculated according to the engine speed detected by the speed sensor 13.

An idle control valve 19 is provided in the first bypass passage 18 that bypasses the throttle valve 20 in order to feedback-control the idle speed to the target value. The control device 11 controls the idle control valve 19 when the air conditioner for air conditioning in the vehicle is activated or when the vehicle shifts from the neutral range to the drive range of the automatic transmission.
The duty of the opening is controlled to increase the amount of intake air, thereby increasing the torque generated by the engine.

The controller 11 calculates the ignition timing of the spark plug 8 according to the fuel injection pulse width corresponding to the engine load and the engine speed so that the optimum ignition timing is obtained according to the operating conditions. The engine coolant temperature sensor 14 and the accelerator opening sensor 16 are used to retard the basic ignition timing in accordance with the activation state of the three-way catalyst 6 when the engine is warmed up.
Alternatively, control is performed according to detection signals from the throttle opening sensor 17, the crank angle sensor 13, the air flow sensor 12, the idle switch 21, and the like.

Until warming-up, such as during a cold start of the engine, the temperature of the three-way catalyst 6 is not activated because the temperature of the three-way catalyst 6 is low. The three-way catalyst 6 is activated at an early stage by delaying the ignition timing based on the accelerator opening and the like so as not to deteriorate the engine operation during warm-up. The amount is corrected and controlled.

In order to prevent a decrease in engine torque due to the ignition timing retard correction, an electromagnetic opening / closing valve 23 is interposed in a second bypass passage 22 that bypasses the throttle valve 20 of the intake passage 2, and the control device 11 determines the ignition timing. During the warm-up period in which the retard control is performed, the electromagnetic on-off valve 23 is energized and opened to compensate for the deterioration of combustion and prevent the engine torque from decreasing.

A rotary switch 24 is interposed in a circuit connecting the control device 11 and the electromagnetic on-off valve 23. Rotation switch 24
Accumulates the pulses sent from the crank angle sensor 13,
The integrated value is compared with a predetermined value, and the relay 25 is configured by a transistor that is turned on and off, and the supply of the drive current through the relay 25 is controlled. The rotation switch 24 may be configured to cut off a drive current sent from the control device 11 to the electromagnetic on-off valve 23 in response to the engine speed rising to a predetermined value or more in conjunction with the engine speed meter. .

As the engine speed rises above a predetermined value, the rotation switch 24 is controlled by the control device 11 to switch the solenoid valve 2.
By shutting off the drive current sent to 3 and forcibly closing the electromagnetic on-off valve 23, even if the control device 11 fails, an increase in the amount of intake air can be suppressed.

As shown in FIG. 2, the control device 11 opens the electromagnetic on-off valve 23 and simultaneously decreases the opening of the idle control valve 17 in a step-like manner, then gradually increases the opening to the original opening. At the same time as opening the electromagnetic on-off valve 23, the opening degree of the idle control valve 17 is increased stepwise and then gradually reduced to the original opening degree. The change in the engine speed may be moderated by spending a certain amount of time in the change in the amount.

[0021]

As described above, the present invention relates to a first bypass passage for leading intake air by bypassing an intake throttle valve in an internal combustion engine that performs ignition timing retard control necessary for activation of a catalyst when cold. A second bypass passage is arranged in parallel, and an idle control valve for adjusting the intake air amount is provided in the first bypass passage so as to feedback-control the idle speed.
An electromagnetic opening / closing valve is interposed in the second bypass passage, and a control device for opening the electromagnetic opening / closing valve in conjunction with the retard control of the ignition timing is provided, and the engine speed is increased to a predetermined value or more. Since the rotary switch for closing the electromagnetic on-off valve is provided accordingly, even if the idle control valve or the control device fails, the increase in the intake air amount after warm-up can be suppressed.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 2 is a control characteristic diagram of an intake air amount.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine main body 2 Intake passage 3 Exhaust passage 6 Catalyst 8 Spark plug 11 Control device 18 First bypass passage 19 Idle control valve 20 Throttle valve 22 Second bypass passage 23 Electromagnetic on-off valve 24 Rotary switch

────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification code FI F02D 43/00 301 F02D 43/00 301B 301L F02P 5/15 F02P 5/15 E (56) References JP-A-2-5740 ( JP, A) JP-A-4-353267 (JP, A) JP-A-6-137246 (JP, A) JP-A-6-26432 (JP, A) JP-A-6-26431 (JP, A) JP JP-A-6-10732 (JP, A) JP-A-5-44555 (JP, A) JP-A-62-189351 (JP, A) JP-A-5-332178 (JP, A) Jpn. , U) JP-B-62-6096 (JP, B2) Patent 2504020 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) F02D 41/06 315 F02D 33/00 F02D 41/16 F02D 43/00 301 F02P 5/15

Claims (1)

(57) [Claims] A first bypass passage and a second bypass passage for bypassing an intake throttle valve and guiding intake air are arranged in parallel in an internal combustion engine that performs ignition timing retard control necessary for activation of a catalyst in a cold state. The first bypass passage is provided with an idle control valve for adjusting the intake air amount so as to feedback-control the idle speed, while the second bypass passage is provided with an electromagnetic opening / closing valve to retard the ignition timing. A control device that opens the electromagnetic on-off valve in conjunction with the control is provided, and the electromagnetic on-off valve is closed when the engine speed rises above a predetermined value in the circuit connecting the control device and the electromagnetic on-off valve. An air amount control device for an internal combustion engine, comprising: a rotation switch for turning on the air.