JPS58170844A - Control method of internal-combustion engine at starting time - Google Patents

Abstract

PURPOSE:To prevent an occurrence of engine stall while a throttle valve being driven to close, by an arrangement such that a secondary air supplying means can be rendered inoperative for a preset time from a time immediately before a throttle valve opening means starts its throttle valve closing action at the latest to a time that the valve closing action is completed. CONSTITUTION:A control circuit 24 actuates electromagnetic valves 15, 21 to operate via driving circuits 22, 23 upon an ignition switch 27 being turned ON. Since a pressure difference in negative pressure chambers 9, 10 is disappeared when the electromagnetic valve 15 is actuated, a control valve 8 is rendered inoperative, and thereby preventing a flow of secondary air to a downstream of throttle valve 5 even when a manifold negative pressure is raised abruptly. Then, the throttle valve 5 is actuated to open upon a starter switch 28 being turned ON, the control circuit 24 verifies as to whether a cranking r.p.m. is reached and thereby rendering the throttle valve to close freely after the first preset time. A secondary air supplying means is rendered inoperative for a second preset time which terminates after the first preset time.

Description

[Detailed description of the invention] The present invention relates to a method for starting an internal combustion engine.

Internal combustion engines are sometimes equipped with a throttle valve opening means such as a cranking opener that automatically increases the amount of intake air when starting the engine to improve startability. The throttle valve is forcibly opened at the same time as the engine is started, and is allowed to close a predetermined time after the engine speed reaches the cranking speed.

Furthermore, in an internal combustion engine, when a throttle valve is suddenly closed during sudden deceleration, the intake manifold negative pressure rapidly increases, and the air-fuel ratio of the intake air-fuel mixture becomes excessively rich.

In order to prevent this, a secondary air supply means, such as a Simit air pulp, is provided to supply atmospheric air to the intake manifold in response to a sudden increase in the intake manifold negative pressure.

However, when the throttle valve opening means enables the throttle valve to close after the predetermined time, unless the driver depresses the accelerator pedal, the intake manifold negative pressure will rise rapidly, causing the secondary air supply means to operate. It is. However, when the throttle valve opening means closes the throttle valve, the operating state of the engine is different because in the case of a cold start, the engine has not warmed up completely, and in the case of a high temperature restart, percolation etc. are likely to occur. Very unstable. In such a case, the air-fuel ratio of the air-fuel mixture may suddenly change in a lean direction due to the supply of secondary air to the intake manifold, causing an engine stall condition.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for controlling the start of an internal combustion engine that can prevent engine stall during the throttle valve closing operation of the throttle valve opening means.

The start-up control method according to the present invention is a method in which the secondary air supply means is kept inactive for a predetermined period of time starting at the latest immediately before the throttle valve closing operation of the throttle valve opening means and ending after the valve closing operation.

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

In FIG. 1, intake air is supplied from an air port 1 to an air filter 2. The air is supplied to the engine 4 via the intake passage 3. A throttle valve 5 is provided in the intake passage 3, and the throttle valve 5
A venturi 6 of the carburetor is formed upstream of the carburetor. Downstream of the throttle valve 5, that is, the intake manifold and the air filter 2
It is configured to communicate with the vicinity downstream of the air passage 7 through an air passage 7. A negative pressure response control valve 8 as a secondary air supply means is provided in the middle of the air passage 7, and the control valve 8 is connected to a negative pressure chamber 9.
．． 10. Diaphragm 11. Consisting of a valve spring 12 and a valve body 13, the valve body 13 is connected to the diaphragm 1 by the valve spring 12.
1 so as to close the air passage 7. The negative pressure chambers 9 and 10 are communicated with each other by an orifice (not shown) formed in the diaphragm 11, but when the negative pressure in the negative pressure chamber 10 suddenly increases, the diaphragm 11 is connected to the valve body 13.
It is designed to be sucked in the direction in which the valve opens. Negative pressure chamber 10
The downstream side of the throttle valve 5 is communicated with the negative pressure passage 14, and the negative pressure passage 14 is also provided so as to communicate with the negative pressure chamber 9 via a solenoid valve 15. The solenoid valve 15 closes the negative pressure passage 14 to the negative pressure chamber 9 when the solenoid 15a is de-energized, and opens the negative pressure passage 14 to the negative pressure chamber 9 when the solenoid 15a is energized.

On the other hand, 16 is a negative pressure responsive throttle valve opening device consisting of a diaphragm 17 and a spring 18.
One negative pressure chamber 19 divided into two chambers communicates with the downstream of the throttle valve 5 through a negative pressure passage 20. The diaphragm 17 is connected to the throttle valve 5 so as to open the throttle valve 5 in response to the negative pressure in the negative pressure chamber 19. A solenoid valve 21 is provided in the middle of the negative pressure passage 2o, and the solenoid valve 21 closes the negative pressure passage 20 when the solenoid 21a is de-energized, and opens the negative pressure passage 20 when it is energized. .

Note that the throttle valve opening device 16 and the solenoid valve 21 constitute throttle valve opening means.

The solenoid 15a is connected to the l1l-circuit 24 through the drive circuit 22, and the solenoid 21a through the drive circuit 23.
is connected. A rotation speed sensor 25 that generates an output voltage at a level corresponding to the engine rotation speed is connected to the control circuit 24, and an output voltage from a battery 26 is supplied via an ignition switch 27. The starter switch 28 is a switch for turning on and off the supply of the output voltage of the battery 26 to a starter motor (not shown) for starting the engine. Next, the operation of the device shown in FIG. 1 when starting the engine will be explained with reference to the operation timing diagram of FIG. 2 and the operation flow diagram of the control circuit 24 of FIG. 3.

First, when the ignition switch 27 is turned on from off as shown in FIG. 2(a), the control circuit 24 operates the solenoid valves 15 and 21 via the drive circuits 22 and 23 (step 1). The negative pressure chambers 9, 1 are opened by the operation of the solenoid valve 15.
Since the zero pressure difference disappears, the control valve 8 becomes inoperative, and secondary air is not supplied downstream of the throttle valve 5 even if the manifold negative pressure rises rapidly. Further, by the operation of the solenoid valve 21, the throttle valve opening valve 116 enables the throttle valve 5 to open.

Next, when the starter switch 28 is turned on and the engine is started, the negative pressure in the intake passage 3 acts on the throttle valve opener 16, the throttle valve 5 is opened, and the control circuit 24 is controlled so that the engine rotation speed Ne is cranked. It is determined whether the rotational speed NCR has been reached (step 2). Then, the engine speed Ne is shown in Figure 2 (b
), when the cranking rotation speed NCR is reached,
A first predetermined time flljcR at which combustion is stabilized after complete explosion of the engine and an excessive increase in engine rotation can be suppressed is counted (step 3). When it is determined that the counting of the time tCR has ended (step 4), the solenoid valve 21 is then put into an inactive state (step 5), and the rate of increase in the negative pressure in the intake passage 3 activates the negative pressure responsive control valve 8. A second predetermined time tSA, which corresponds to the time during which the value decreases to a value that does not occur, is counted (step 6).

When the electromagnetic valve 21 stops driving, the negative pressure passage 20 is closed, so the throttle valve opening device 16 allows the throttle valve 5 to close freely.

Next, after the throttle valve 5 is closed, when the control circuit 24 determines that the counting of the time tSA has ended (step 7), the solenoid valve 15 is put into an inoperable state (step 8), and when the drive of the solenoid valve 15 is stopped. Since the negative pressure passage 14 to the negative pressure chamber 9 is closed, the control valve 8 opens the air passage 7 in response to a sudden increase in the intake manifold negative pressure to supply secondary air downstream of the throttle valve 5.

Note that FIG. 2(e) shows the operating state of the solenoid valve 21 and the second state.
Figure (d) shows the solenoid valve 15 when it is in operation.

As described above, according to the startup control method according to the present invention, the secondary air supply means is kept in an inoperable state from immediately before the closing operation of the throttle valve opening means until the elapse of the second predetermined time period at which the valve closing operation ends. Therefore, secondary air is not supplied to the intake manifold during the throttle valve closing operation of the throttle valve opening means.
It is possible to prevent the air-fuel ratio of the air-fuel mixture from rapidly changing toward the lean direction. Therefore, engine stall is prevented during this throttle valve closing operation.

Furthermore, in the start-up control method of the present invention, the period during which the secondary air supply means is kept inactive is from at the latest immediately before the throttle valve closing operation of the throttle valve opening means until after a second predetermined period has elapsed. However, as in the above embodiment, by setting the period from turning on the ignition switch to the elapse of the second predetermined timing, the throttle valve opening operation of the throttle valve opening means due to a sudden increase in engine speed immediately after starting can be avoided. This makes it possible to better prevent engine stall due to a lean air-fuel ratio.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an internal combustion engine control device using the start-up control method according to the present invention, and FIG. 2 (a to d) is an operation timing diagram of the device in FIG. 1. FIG. 3 is an operational flow diagram of the control circuit. Explanation of symbols of main parts 1...Atmospheric port 3...Intake path 5
... Throttle valve 8 ... Control valve 15
．． 21... Solenoid valve 16... Throttle valve opener 27... Ignition switch 28...
...Starter switch applicant Honda Motor Co., Ltd. agent Patent attorney Motohiko Fujimura Back figure 2 rod, figure 3

Claims (2)

[Claims] (1) A throttle valve opening means that opens the throttle valve at the time of engine startup and freely closes the throttle valve after a first predetermined period after the engine speed reaches the cranking speed, and an intake manifold. A control method at the time of starting an internal combustion engine, comprising a secondary air supply means for supplying atmospheric air to the intake manifold in response to a sudden increase in negative pressure, the method comprising: a secondary air supply means for supplying atmospheric air to the intake manifold in response to a sudden increase in negative pressure; 2. A start-up control method, characterized in that the secondary air supply means is rendered inoperative only for a second predetermined time that ends after the first predetermined time. (2) The start-up control method according to claim 1, characterized in that the secondary air supply means is kept in an inoperable state from when the ignition switch is turned on until the second predetermined time period passes.