JPH0771293A - Idle rotational speed control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve engine rotational speed at the time of idle operation so as to prevent generation of engine stall by controlling a bypass control valve in prescribed opening condition when fuel whose amount is increased and corrected by an increasing and correcting coefficient after an engine is started at a high temperature is injected from a fuel injection valve after the engine is started at the high temperature. CONSTITUTION:In an internal combustion engine provided with a bypass passage 24 interposed a bypass control valve 26 which is duty-controlled so as to bypass the intake throttle valve 10 in an intake air passage 4, a cooling water temperature judging value and an intake air temperature judging value are set when the bypass control valve 26 is controlled by a control unit 40. When an internal combustion engine 2 is started, the cooling water temperature and the cooling water temperature judging value are compared with an intake air temperature and the intake air temperature judging value so as to judge whether it is high temperature starting or not. When it is judged that a fuel amount is increased and corrected by an increasing and correcting coefficient after the engine 2 is started at a high temperature, the bypass control valve 26 is controlled so as to maintain the bypass passage 24 in prescribed opening condition, and an bypass air amount is increased so as to increase idle rotational speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an idle speed control device for an internal combustion engine, and more particularly to an idle speed control method for an internal combustion engine which can reduce fluctuations in rotation of the internal combustion engine after a high temperature start and prevent engine stall. Number control device.

[0002]

2. Description of the Related Art Some internal combustion engines mounted on vehicles or the like are equipped with an idle speed control device for controlling the engine speed to a target speed during idle operation. The idle speed control device includes a bypass passage that bypasses the intake throttle valve of the internal combustion engine and communicates with the intake passage, a bypass control valve that opens and closes the bypass passage, and opens and closes the bypass passage during idle operation of the internal combustion engine. The operation of the bypass control valve is feedback-controlled by the duty ratio so that the engine speed becomes the target speed.

Examples of the idle speed control device for the internal combustion engine include Japanese Patent Laid-Open No. 62-10433 and Japanese Utility Model Laid-Open No. 62-62.
There is one disclosed in Japanese Patent Publication No. 200114.

The idle speed control device disclosed in Japanese Unexamined Patent Publication No. 62-10433 increases the intake air amount when the temperature of the internal combustion engine is equal to or higher than a predetermined temperature at the time of starting the internal combustion engine, and after a predetermined time after the start. When the engine speed has passed, or when the engine speed exceeds a predetermined speed, the intake air amount is controlled to be decreased.

The idle speed control device disclosed in Japanese Utility Model Laid-Open No. Sho 62-200141 discloses a system in which the duty ratio is set to a predetermined time after the bypass control valve is started based on the cooling water temperature and the intake air temperature of the internal combustion engine. A duty ratio setting means is provided.

Some internal combustion engines have a fuel injection valve in the intake passage. The fuel injection valve injects fuel in which the basic injection amount is corrected by various correction coefficients according to the operating state of the internal combustion engine, and is controlled so that the air-fuel ratio becomes the target air-fuel ratio.

[0007]

By the way, an internal combustion engine may generate fuel vapor in a fuel injection valve due to engine residual heat when the drive is stopped after high temperature and high load operation. In particular, an internal combustion engine equipped with a supercharger has severe thermal conditions, so when stopping after high temperature / high load operation,
Fuel vapor is easily generated in the fuel injection valve.

Therefore, when the internal combustion engine is stopped at high temperature and under high load and then the driving is stopped, and the internal combustion engine is restarted in a high temperature state before being sufficiently cooled, it is generated in the fuel injection valve. The injection of the fuel vapor makes the air-fuel ratio lean and causes fluctuations in rotation, which easily causes engine stall.

Therefore, conventionally, it is determined whether or not the fuel vapor is generated based on the conditions such as the cooling water temperature and the intake air temperature at the time of starting, and as shown in FIG. When the engine is started in this state, the fuel that has been increased and corrected by the high-temperature post-startup increase correction coefficient FHS is injected from the fuel injection valve, and the air-fuel ratio is tilted to the rich side to prevent engine stall.

However, in the conventional idle rotation control device, as shown in FIG. 4 (a), the idle injection of the fuel by the evaporated fuel after the high temperature start in the state where the fuel vapor is generated in the fuel injection valve is performed. That is, due to the injection of the fuel vapor from the fuel injection valve, the idle rotation speed control has a poor followability with respect to a sudden decrease in rotation when the air-fuel ratio becomes lean,
There is an inconvenience that an engine stall is likely to occur.

That is, as shown in FIG. 4B, the internal combustion engine in the high temperature state immediately after the driving is stopped, immediately after the start of the cranking and the complete explosion, immediately after the start of the fuel injection valve, the increase correction coefficient after the high temperature start is corrected. The injection of the fuel whose amount has been corrected by FHS is started, and the air-fuel ratio is tilted to the rich side. The increase correction coefficient FHS after high temperature start is a value determined by the cooling water temperature, and is decreased by a fixed amount for each injection.

At this time, the idle speed control device, as shown in FIG. 4 (c), immediately after the start of the complete combustion of the internal combustion engine,
The operation of the bypass control valve is controlled so that the bypass passage is temporarily fully opened. The fully open time for temporarily fully opening the bypass passage is determined by the cooling water temperature. The idle speed control device feedback-controls the operation of the bypass control valve by the duty ratio so that the engine speed becomes the target speed after the full opening time has elapsed, and opens and closes the bypass passage.

However, since the conventional idle speed control device controls the operation of the bypass control valve so that the engine speed becomes the target speed after the temporary full opening time, the operation shown in FIG. As shown in FIG. 4C), when the air-fuel ratio becomes lean due to the idle injection of the fuel by the evaporated fuel after the high temperature start, and a sudden decrease in rotation is caused, FIG. As shown in the figure, there is a problem that the idle speed control has poor followability, large rotation fluctuations occur, and engine stall is likely to occur.

[0014]

In order to solve such inconvenience, the present invention provides a fuel injection valve in the intake passage of an internal combustion engine and bypasses the intake throttle valve of the internal combustion engine to introduce the intake passage. A bypass control valve for opening and closing the bypass passage is provided for injecting fuel corrected by various correction coefficients according to the operating state of the internal combustion engine so that the air-fuel ratio becomes the target air-fuel ratio. An idle rotation control device for an internal combustion engine, which controls the operation of the fuel injection valve and controls the operation of the bypass control valve so that the engine speed becomes a target speed by opening and closing the bypass passage during idle operation of the internal combustion engine. In the case where the fuel whose injection amount is corrected by the increase correction coefficient after high temperature injection is injected from the fuel injection valve after the internal combustion engine is started at high temperature, the bypass passage is Characterized in that a control means for controlling the operation of the bypass control valve so as to maintain a constant open state.

[0015]

According to the structure of the present invention, the idle speed control device is configured so that, after the internal combustion engine is started at high temperature,
When injecting the fuel whose amount has been increased and corrected by the increase correction coefficient after high temperature startup from the fuel injection valve, by controlling the operation of the bypass control valve to maintain the bypass passage in the predetermined open state, after the high temperature start of the internal combustion engine A sufficient amount of air can be secured by the bypass passage maintained in the predetermined open state, and the engine speed during idle operation can be increased.

[0016]

Embodiments of the present invention will now be described in detail with reference to the drawings.

1 to 3 show an embodiment of the present invention. In FIG. 3, 2 is an internal combustion engine, 4 is an intake passage, and 6 is an exhaust passage. The intake passage 4 of the internal combustion engine 2 mounted on a vehicle (not shown) has an air cleaner 8 at the upstream end and communicates the downstream end with a combustion chamber (not shown). An intake throttle valve 10 is provided in the intake passage 4.

A fuel injection valve 12 is provided in the intake passage 4 of the internal combustion engine 2 so as to face a combustion chamber (not shown). The fuel injection valve 12 communicates with a fuel tank 16 via a fuel passage 14. A fuel pump 18 for supplying fuel to the fuel passage 14 is provided in the fuel tank 16. A fuel pressure adjusting valve 20 for adjusting the fuel pressure by the intake pressure of the intake passage 4 is provided in the middle of the fuel passage 14. The fuel pressure adjusting valve 20 adjusts the fuel pressure in the fuel passage 14 to a predetermined pressure, and returns excess fuel to the fuel tank 16 through the return passage 22.

The intake passage 4 is provided with a bypass passage 24 that bypasses the intake throttle valve 10. Bypass passage 2
4, one end communicates with the intake passage 4 upstream of the intake throttle valve 10, and the other end communicates with the intake passage 4 reaching a combustion chamber (not shown) downstream of the intake throttle valve 10. is doing. The bypass passage 24 is provided with a bypass control valve 26 which is controlled by the duty ratio according to the operating state of the engine 2.

The intake passage 4 is provided with a throttle sensor 28 for detecting the opening of the intake throttle valve 10, an intake temperature sensor 30 for detecting the intake temperature, and an intake pressure sensor 32 for detecting the intake pressure. There is. In the internal combustion engine 2,
A rotation angle sensor 34 and a cooling water temperature sensor 36 that detects the cooling water temperature are provided. The rotation angle sensor 34 is provided in the distributor 38. These various sensors 28 to 36 are connected to the input side of a control unit 40 which is a control means that constitutes an idle speed control device.

On the input side of the control section 40, a diagnosis signal section 42 for inputting a diagnosis signal is also input.
And the air conditioner (air conditioner: not shown) turned on
・ Air conditioner switch 44 to input the OFF signal,
A speedometer 46 for inputting a vehicle speed signal, an initial set portion 48 for inputting an initial set signal,
An O ₂ sensor 50 provided in the exhaust passage 6, a CO adjustment resistor section 52 for inputting a CO adjustment signal, and a battery 54
And are connected.

On the output side of the control unit 40, the fuel injection valve 12, the fuel pump 18, the bypass control valve 26,
Are connected. The fuel pump 18 is a pump relay 5
It is connected via 6. An ignition coil 58, a monitor 60, and a duty meter 62 are connected to the output side of the control unit 40.

The control unit 40 includes various sensors 28 to 36.
The fuel injection valve 12 outputs an injection valve drive signal to the fuel injection valve 12, a pump drive signal to the fuel pump 18, an ignition command signal to the ignition coil 58, and an appropriate fuel from the fuel injection valve 12. Inject and fire a spark plug (not shown) appropriately.

The control unit 40 includes various sensors 28 to 36.
The fuel input valve 12 controls the operation of the fuel injection valve 12 so that the air-fuel ratio becomes the target air-fuel ratio by injecting fuel whose basic injection amount is corrected by various correction coefficients according to the operating state of the internal combustion engine 2 by a signal input from Adjust the injection amount. In addition, the control unit 4
0 indicates the bypass passage 24 when the internal combustion engine 2 is idle.
Is opened and closed to feedback control the operation of the bypass control valve 26 by the duty ratio so that the engine speed becomes the target speed, and the amount of bypass air in the bypass passage 24 is adjusted.

This idle speed control device includes a control unit 4
0 causes the fuel injection valve 1 to
When the fuel whose amount has been increased and corrected by the increase correction coefficient FHS after high temperature start is being injected from 2 on, the operation of the bypass control valve 24 is controlled so as to maintain the bypass passage 24 in the predetermined open state.

The control unit 40 is provided with a cooling water temperature judgment value A for the cooling water temperature THW and an intake air temperature judgment value B for the intake air temperature THA. When the internal combustion engine 2 is started, the control unit 40 compares the cooling water temperature THW and the cooling water temperature determination value A with the intake air temperature THA and the intake air temperature determination value B to determine whether or not the engine is a high temperature startup, After the startup, when the increase correction is performed by the high temperature after-start increase correction coefficient FHS, the operation of the bypass control valve 26 is fixed duty ratio controlled in order to maintain the bypass passage 24 in the predetermined open state, and the bypass air amount is increased to idle. Increase the rotation speed.

Next, the operation will be described.

In the internal combustion engine 2, the air taken in from the air cleaner 8 is metered and supplied by the intake throttle valve 10, the fuel is supplied by the fuel injection valve 12, and the fuel is ignited and burned by an ignition plug (not shown). . The fuel supply amount and the ignition timing are appropriately controlled by the control unit 40.

The idle speed control device controls the operation of the fuel injection valve 12 by the control unit 40 so that the air-fuel ratio becomes the target air-fuel ratio when the internal combustion engine 2 is in operation. The feedback control of the operation of the bypass control valve 26 is performed by the duty ratio so that the value becomes the target rotation speed.

When the internal combustion engine 2 is started, this idle speed control device operates as follows by bypass control valve 26.
To control.

As shown in FIG. 1, the control unit 40 turns on an ignition switch (not shown) to start the internal combustion engine 2 that is stopped (step 100), and the cooling water detected by the cooling water temperature sensor 36 is detected. It is determined whether or not the temperature THW is equal to or higher than the cooling water temperature determination value A (step 102).

When the cooling water temperature THW is equal to or higher than the cooling water temperature determination value A, it is determined whether or not the intake temperature THA detected by the intake temperature sensor 30 is equal to or higher than the intake temperature determination value B (step 104).

When the cooling water temperature THW is equal to or higher than the cooling water temperature determination value A and the intake air temperature THA is equal to or higher than the intake temperature determination value B, the internal combustion engine 2 produces evaporated fuel in the fuel injection valve 12. There is a risk of high temperature.

When the internal combustion engine 2 in such a high temperature state is started, the internal combustion engine 2 is started (step 106).
After the complete explosion, the fuel (FHS: O
(N) is injected (step 108), and the operation of the bypass control valve 26 is fully opened (step 110) so as to temporarily fully open the bypass passage 24.

The fully open time for temporarily opening the bypass passage 24 is determined by the cooling water temperature THW. When this fully open time has elapsed, the operation of the bypass control valve 26 is fixed duty ratio controlled (step 112) in order to maintain the bypass passage 24 in the predetermined open state. As a result, the idle speed control device can increase the bypass air amount to increase the idle speed and prevent engine stall.

Next, it is judged whether the increase correction coefficient FHS after high temperature start is larger than 0 (zero) (step 11).
4) Do. The increase correction coefficient FHS after high-temperature start is a value determined by the cooling water temperature THW, and is decreased by a constant amount for each injection to 0 (zero). In the determination as to whether or not the high temperature after-start amount increase correction coefficient FHS is larger than 0 (zero) (step 114), if the high-temperature after-start amount increase correction coefficient FHS is larger than 0 (zero), the bypass passage 24 is set to a predetermined position. Step 1 of controlling the operation of the bypass control valve 26 with a fixed duty ratio so as to maintain the open state
Return to 12.

After the high temperature start, the increase correction coefficient FHS is 0.
Judgment whether it is greater than (zero) (step 114)
At high temperature, the increase correction coefficient FHS after high temperature start is 0 (zero)
In this case, the fixed duty ratio control for maintaining the bypass passage 24 in the predetermined open state is terminated, and the bypass passage 2
4 is opened / closed to perform feedback control (step 124) of the operation of the bypass control valve 26 with a normal duty ratio so that the engine speed becomes the target speed.
Adjust the bypass air amount of 4.

On the other hand, in determining whether the cooling water temperature THW is equal to or higher than the cooling water temperature determination value A (step 102), the cooling water temperature THW is determined to be the cooling water temperature determination value A.
If the cooling water temperature THW is equal to or higher than the cooling water temperature determination value A, it is determined whether the intake air temperature THA is equal to or higher than the intake temperature determination value B (step 104).
When the intake air temperature THA is lower than the intake air temperature determination value B, the internal combustion engine 2 is not in a high temperature state and is sufficiently cooled.

When the internal combustion engine 2 in such a cooled state is started, the internal combustion engine 2 is started (step 116).
Then, after the complete explosion, the increase correction by the increase correction coefficient FHS after high temperature start is not performed (FHS: OFF) (step 11
8), the operation of the bypass control valve 26 is controlled so that the fuel is injected from the fuel injection valve 12 after being corrected by the normal correction coefficient, and the bypass passage 24 is temporarily fully opened (step 120).
To do.

The full open time for temporarily opening the bypass passage 24 is determined by the cooling water temperature THW. When this fully open time has elapsed, the operation of the bypass control valve 26 is fixed duty ratio controlled (step 122) in order to maintain the bypass passage 24 in the predetermined open state. The control time based on this fixed duty ratio is determined by the cooling water temperature THW and the like.

When the control time with the fixed duty ratio has elapsed, the fixed duty ratio control for maintaining the bypass passage 24 in the predetermined open state is completed, and the bypass passage 24 is closed.
Is opened and closed to feedback control the operation of the bypass control valve 26 by the duty ratio so that the engine speed becomes the target speed (step 124), and the amount of bypass air in the bypass passage 26 is adjusted.

As described above, in the idle speed control device, the control unit 40 controls the internal combustion engine 2 to start at a high temperature.
As shown in FIG. 2B, when the fuel injection valve 12 is injecting the fuel whose amount has been increased and corrected by the increase correction coefficient FHS after hot start, the bypass passage 24 is fully opened as shown in FIG. 2C. The operation of the bypass control valve 26 is controlled to a fixed duty ratio by a fixed duty ratio so as to maintain a predetermined open state close to

As a result, after the internal combustion engine 2 is started at high temperature,
Bypass passage 24 maintained in a predetermined open state close to full open
As a result, a sufficient amount of air can be secured, and the engine speed during idle operation can be increased.

Therefore, after the internal combustion engine 2 is started at a high temperature, as shown in FIG. 2A, when the air-fuel ratio becomes lean due to the air injection of the fuel by the evaporated fuel, the rotation due to the influence of the lean air-fuel ratio. The decrease can be reduced. This makes it possible to reduce fluctuations in rotation and prevent engine stall.

Further, in this idle speed control device, the control unit 40 maintains the bypass passage 24 in a predetermined open state close to full open by the fixed duty ratio control, so that a large change of the control program is required. Instead, it can be implemented with a small number of steps, can be implemented with small program changes, and can be easily applied to existing equipment.
It is practically advantageous.

[0046]

As described above, according to the present invention, a sufficient amount of air can be secured by the bypass passage maintained in the predetermined open state after the internal combustion engine is started at a high temperature, and the engine speed during idle operation is increased. be able to. Therefore, after the internal combustion engine is started at a high temperature, it is possible to reduce the decrease in rotation when the air-fuel ratio becomes lean due to the idle injection of the fuel with the evaporated fuel.
This makes it possible to reduce fluctuations in rotation and prevent engine stall.

[Brief description of drawings]

FIG. 1 is a flow chart of control by an idle speed control device showing an embodiment of the present invention.

FIG. 2A is a diagram showing a change in engine speed after a high temperature start. (B) is a figure which shows the change of the increase correction coefficient after high temperature start after high temperature start. (C) is a figure which shows the change of the duty ratio after a high temperature start.

FIG. 3 is a schematic configuration diagram of an idle speed control device for an internal combustion engine.

FIG. 4A is a diagram showing a change in engine speed after a conventional high temperature start. (B) is a figure which shows the change of the increase correction coefficient after high temperature start after the conventional high temperature start.
(C) is a figure which shows the change of the duty ratio after the conventional high temperature start.

[Explanation of symbols]

 2 internal combustion engine 4 intake passage 6 exhaust passage 10 intake throttle valve 12 fuel injection valve 24 bypass passage 26 bypass control valve 30 intake temperature sensor 36 cooling water temperature sensor 40 control unit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location F02D 45/00 312 Q 345 C

Claims (1)

[Claims] 1. A fuel injection valve is provided in an intake passage of an internal combustion engine, a bypass passage is provided that bypasses the intake throttle valve of the internal combustion engine and communicates with the intake passage, and a bypass control valve that opens and closes the bypass passage is provided. The operation of the fuel injection valve is controlled so that the air-fuel ratio becomes the target air-fuel ratio by injecting the fuel corrected by various correction coefficients according to the operating state of the internal combustion engine, and the bypass passage is opened during the idle operation of the internal combustion engine. In an idle speed control device for an internal combustion engine, which opens and closes to control the operation of the bypass control valve so that the engine speed becomes a target speed, an increase correction after hot start from the fuel injection valve after hot start of the internal combustion engine A control means for controlling the operation of the bypass control valve in order to maintain the bypass passage in a predetermined open state when injecting fuel whose amount is increased by a coefficient is being injected. An idle speed control device for an internal combustion engine, which is provided.