JPH0539743A - Internal combustion engine with fuel injection device - Google Patents

Abstract

PURPOSE:To prevent engine revolution from being excessively increased when an air control valve fails to be opened, and when control by an ISC is beyond its limit in an engine equipped with the ICS system which regulates an air flow rate within a bypass passage bypassing an inlet air throttle valve, and with a fuel injection valve device having an air assist passage provided with an air control valve halfway. CONSTITUTION:This is an internal combustion engine with a fuel injection device equipped with a bypass passage 4 going around an inlet air throttle valve 2, an air supply passage 6 assisting fuel injected from fuel injection valves 3a through 3d with air while the respective passages 4 and 6 are provided with an idle revolution control valve 5 and air control valves 7a through 7d. And the revolution increase restraining means is provided, which lowers the engine in revolution to an idle operating condition where the opening of an idle revolution control valve 5 is less than a specified one, and engine revolution is equal to or more than a specified one.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides an internal combustion engine having an engine idle speed control device with a fuel injection device having an auxiliary air supply device for atomizing injected fuel.

[0002]

2. Description of the Related Art A bypass passage for bypassing an intake throttle valve provided in an intake passage and an idle speed control valve for controlling an idle speed by adjusting a flow rate of air flowing through the bypass passage when the intake throttle valve is fully closed. An internal combustion engine equipped with an idle speed control device is known in the art. Further, a fuel injection valve installed to inject fuel into the intake passage is provided,
A fuel injection device that atomizes the fuel by supplying auxiliary air to the fuel injected from the fuel injection valve is also well known. For example, the fuel injection device provided in the internal combustion engine with the idle speed control device is, for example, actually used. It is disclosed in Kaihei 2-24069.

To explain such a conventional technique with reference to FIG. 6, intake air sucked from an air cleaner (not shown) and having its flow rate measured by an air flow meter (not shown) flows through an intake passage 1 of an internal combustion engine. In the intake passage 1,
Intake throttle valve 2 for adjusting the flow rate of air passing through the intake passage 1
Is installed. A fuel injection valve 3 for injecting fuel into the intake passage 1 is installed in the intake pipe 1a. Also, reference numeral 8
Is an intake valve, and the intake port 1b of the cylinder head 10
It is located downstream.

A bypass passage 4 for bypassing the intake throttle valve 2 is attached to the intake pipe 1a, and the flow rate of air passing through the bypass passage 4 is controlled in the bypass passage 4 when the intake throttle valve 2 is fully closed to control the engine idle speed. The idle speed control valve 5 is installed.

The idle speed control valve 5 is controlled in the closing direction when the engine idle speed exceeds a predetermined value. Then, the amount of air flowing through the bypass passage 4 decreases and the engine idle speed decreases. When the engine idle speed falls below a predetermined value, the idle speed control valve 5 is controlled to open, the amount of air flowing through the bypass passage 4 increases, and the engine idle speed increases. In this way, the idle speed control device controls the engine idle speed when the intake throttle valve 2 is closed to a predetermined value by the control means (not shown).

The intake throttle valve 2 is attached to the tip of the fuel injection valve 3.
An air supply passage 6 for guiding the auxiliary air from the upstream side is provided, and atomization of the fuel is achieved by colliding the injected fuel with the auxiliary air flow. An air control valve 7 for adjusting the flow rate of auxiliary air flowing through the air supply passage 6 is provided in the air supply passage 6. The air control valve 7 is opened and closed by an actuator 9 such as a step motor or an electromagnetic solenoid. The opening / closing timing of the air control valve 7 is performed by synchronizing with various engine conditions, for example, fuel injection.

[0007]

In such a conventional technique, the actuator 9 fails when the air control valve 7 is open, or the driving force transmission system from the actuator 9 to the air control valve 7 fails. Then, the air control valve 7 may be left open (hereinafter referred to as open failure). When the air control valve 7 has an open failure, the intake throttle valve 2 is connected through the air supply passage 6 to the upstream side and the downstream side of the intake throttle valve 2. When the idle speed control is performed in this state and the bypass passage 4 is closed by the idle speed control valve 5 when the idle speed is increased, air is shown from the air supply passage 6 which is separate from the bypass passage 4. Since it is sucked into the combustion chamber which is not present, there is a risk that the engine speed will rise more than necessary. Then, there arises a problem that the fuel consumption rate is deteriorated.

Therefore, an object of the present invention is to prevent the engine speed from rising excessively when the air control valve provided in the auxiliary air supply passage for atomizing the injected fuel fails to open in the internal combustion engine as described above. It is to be.

[0009]

In order to achieve the above object, according to the present invention, an intake throttle valve provided in an intake passage, a fuel injection valve for injecting fuel into an intake passage downstream of the intake throttle valve, and the intake air A bypass passage for bypassing the throttle valve is provided, and an idle speed control valve whose opening is adjusted to maintain the engine speed at a first predetermined value when the intake throttle valve is closed is installed in the bypass passage, and the fuel injection is performed. In an internal combustion engine with a fuel injection device, comprising an air supply passage separate from the bypass passage for supplying air to fuel injected from a valve, and an air control valve for adjusting an air flow rate flowing in the air supply passage. An idle speed control valve opening detection means for detecting the idle speed control valve opening during engine idle operation; a rotation speed detection means for detecting an engine speed; and the idle speed control valve Degrees is the provision of a suppressing rotational speed increase suppression means an increase in the engine speed when it is high the second predetermined value or more than it and the engine speed is the first predetermined value or less than a predetermined value.

[0010]

According to the present invention, when the idling speed control valve opening is equal to or less than a predetermined value during idling and the engine speed is equal to or higher than a second predetermined value which is higher than the first predetermined value, the idle speed control valve is opened. The rotation speed is not maintained at the first predetermined value, and the upstream and downstream of the intake throttle valve are still in communication with each other via an air supply passage that is separate from the bypass passage, that is, when the air control valve fails to open. Since the increase in engine speed is suppressed by the engine speed increase suppressing means when the air control valve is open, the engine speed does not rise too much.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment according to the present invention will be described below with reference to FIGS. The same components as those in FIG. 6 are designated by the same reference numerals and the description thereof will be omitted. Long nozzles 31 for injecting fuel in the vicinity of the intake valve 8 are attached to the fuel injection valves 3a to 3d provided for each cylinder, and the fuel in the long nozzles 31 is surrounded by the long nozzles 31. A PTC heater 32 is provided to accelerate the atomization of fuel by heating.
Note that, in FIG. 1, the fuel injection valves 3b, 3c, 3d other than the fuel injection valve 3a are shown in a simplified diagram. Hereinafter, the contents common to the fuel injection valves 3a to 3d will be appropriately described as the fuel injection valve 3. In the air supply passage 6 for supplying air to the fuel from each of the fuel injection valves 3a to 3d, the air from the upstream opening 6a is distributed by the delivery pipe 21 to each of the fuel injection valves 3a to 3d. An air pump 11 driven by engine rotation is installed upstream of the delivery pipe 21 in the air supply passage 6 to compress the air flowing in from the upstream opening 6a of the air supply passage 9 and to use the compressed air as fuel. By colliding with the fuel injected from the injection valve 3, further atomization is achieved.

An air passage 19 is branched from the air supply passage 6, and a pressure control valve 16 is installed in the air passage 19. The pressure control valve 16 is connected to the downstream side of the intake throttle valve 2 through a path (not shown). Such a pressure control valve 1
Reference numeral 6 is a known one for making the differential pressure between the air pressure in the air supply passage 6 pressurized by the air pump 11 and the downstream pressure of the intake throttle valve 2 constant.

The air control valves 7a to 7d provided downstream of the delivery pipe 21 are driven by actuators 9a to 9d such as electromagnetic solenoids, and the opening and closing timings of the air control valves 7a to 7d depend on engine conditions such as fuel injection. It is done by synchronizing. The idle speed control valve 5 is driven by the step motor 14. Actuators 9a to 9d and step motor 1
Driving of the electronic control unit 4 is controlled by an electronic control circuit (ECU) 20. It should be noted that, in FIG. 1, components other than the air control valve 7a and the actuator 9a are illustrated in a simplified manner.

The throttle sensor 12 detects the opening of the intake throttle valve 2, the engine rotation sensor 13 detects the engine speed, and the opening of the idle speed control valve 5. For ISCV opening sensor 1
5 are installed respectively, the ECU 20 reads the input signals from the respective sensors, and based on them, the actuator 9
a to 9d and the step motor 14 are driven. Further, the ECU 20 controls the amount of fuel injected from the fuel injection valve 3 so as to perform air-fuel ratio control according to the operating state based on an input value from an air flow meter (not shown). The idle speed control valve 5 is conventionally controlled by a known idle speed control program stored in the ECU 20 so that the engine speed is maintained near the first predetermined value when the intake throttle valve 2 is fully closed. There is.

A flow chart of the program of the first embodiment stored in the ECU 20 will be described with reference to FIG. This routine in the first embodiment is a time interruption routine which is generated every predetermined time. Step 100 is the starting point of the program. In step 101, it is judged from the input signal from the throttle sensor 12 whether or not the engine is idling. That is, when the intake throttle valve 2 is fully closed, it is during idle operation, so it is determined that the idle switch is in the ON state, and the routine proceeds to step 102. If the intake throttle valve 2 is open, the idle switch is OFF in step 101, so the routine branches to step 105 and this routine ends.

When it is determined in step 101 that the idle switch is in the ON state and the routine proceeds to step 102, this time, the ISCV opening sensor 1 for detecting the opening of the idle speed control valve 5 is detected.
Based on the signal from 5, it is determined whether the opening degree of the idle speed control valve 5 is less than or equal to a predetermined value. Here, the predetermined value of the opening of the idle speed control valve 5 is a value near the opening when the idle speed control valve 5 is substantially fully closed. YE in step 102
If S, that is, if the opening degree of the idle speed control valve 5 is less than or equal to a predetermined value, the routine proceeds to step 103, where the engine speed sensor 1
A first predetermined value (for example, about 800 revolutions) that is the engine revolution speed target value of the engine revolution speed by the input signal from 3
It is determined whether or not it is equal to or higher than a second predetermined value (for example, about 1600 rotations) which is a higher rotation speed. If the engine speed is equal to or higher than the second predetermined value, the process proceeds to step 104,
The fuel injection valve 3 is operated to stop the fuel injection, and then the routine proceeds to step 105 and the present routine is ended. If NO is determined in step 102 or step 103, the process branches to step 105 and this routine is also ended.

Here, the first predetermined value of the engine speed may be controlled so as to change according to the engine state (idle-up control or the like), but in that case, the second predetermined value is set to the first predetermined value. It should be larger than the maximum possible value.

FIG. 3 shows a drive timing chart of the fuel injection valve 3 and the air control valve 7 of this embodiment. T
₃ is the fuel injection valve 3 opening time, T ₇₁ is the air control valve 7
Is the valve opening time. As can be seen from FIG. 3, the opening / closing drive of the air control valve 7 is synchronized with the opening / closing drive of the fuel injection valve 3, and the air control valve 7 is opened earlier than the fuel injection valve 3 by a predetermined timing and the fuel injection is performed. The drive signal is generated so that the air control valve 7 is closed after the valve 3 is closed.

In the first embodiment described above, E
According to the routine stored in the CU 20 and shown in FIG. 2, when the engine is idling and the idle speed control valve 5 opening degree is equal to or less than a predetermined value and the engine speed is equal to or higher than a second predetermined value higher than the first predetermined value , The idle speed is not maintained at the first predetermined value, and the upstream and downstream sides of the intake throttle valve remain in communication via an air supply passage separate from the bypass passage, that is, the air control valve is opened. It is considered to be a time of failure, and the fuel supply from the fuel injection valve 3 is stopped when the air control valve is open, so an increase in engine speed can be avoided.

The second embodiment will be described below with reference to the flow chart of FIG. The entire system of the second embodiment is the same as that of FIG. 1 of the first embodiment. Step 10
0 to step 103 and step 105 are the same as those in FIG. If YES in step 103, that is, if the engine idling operation is performed and the idling speed control valve 5 opening degree is equal to or less than the predetermined value and the engine speed is equal to or greater than the second predetermined value
The routine proceeds to step 106, where the valve opening time of the air control valves 7a to 7d is shortened.

The valve opening time shortening process in step 106 will be described with reference to the timing chart shown in FIG. In FIG. 5, T ₃ and T ₇₁ are the opening times of the fuel injection valve 3 and the air control valve 7, respectively, as in FIG. 3, but if the valve opening time shortening process is performed, the opening time of the air control valve 7 will be Shortened from T ₇₁ to T ₇₂ .

In the second embodiment described above, for example, even if the air control valve 7a has an open failure, the opening time of the other air control valves 7b to 7d which are not open failure is shortened, so that each cylinder is opened. In all, the amount of air taken in through the air supply passage 6 can be reduced, and an increase in engine idle speed can be prevented.

Further, as another embodiment, when an air control valve fails to open, the opening degree of the other air control valve can be controlled to be small.

Further, in this embodiment, the ISCV opening sensor 1
However, if the opening degree of the idle speed control valve 5 is stored in the ECU 20, the ISCV opening degree sensor 15 may not be provided.

[0025]

As described above, according to the present invention, since the engine speed is suppressed by the engine speed suppressing means when the air control valve is open, the engine speed does not rise excessively, and the fuel consumption rate is reduced. Will never worsen.

[Brief description of drawings]

FIG. 1 is a system diagram of a first embodiment.

FIG. 2 is a control flowchart of the first embodiment.

FIG. 3 is a timing chart of the first embodiment.

FIG. 4 is a control flowchart of the second embodiment.

FIG. 5 is a timing chart of the second embodiment.

FIG. 6 is an internal combustion engine with an idle speed control device that includes a conventional fuel injection device with an auxiliary air supply system.

[Explanation of symbols]

 2 ··· Intake throttle valve 3 ··· Fuel injection valve 4 ··· Bypass passage 5 ··· Idle speed control valve 6 ··· Air supply Passage 7 ・ ・ ・ ・ ・ ・ Air control valve 11 ・ ・ ・ ・ ・ Air pump 16 ・ ・ ・ ・ ・ Pressure control valve

Claims (1)

[Claims] 1. An intake throttle valve having an intake throttle valve provided in an intake passage, a fuel injection valve for injecting fuel into an intake passage downstream of the intake throttle valve, and a bypass passage bypassing the intake throttle valve. An idle speed control valve, the opening of which is adjusted to maintain the engine speed at a first predetermined value when closed, is installed in the bypass passage, and the bypass passage for supplying air to the fuel injected from the fuel injection valve. In an internal combustion engine with a fuel injection device, which is provided with an air supply passage separate from and an air control valve for adjusting the flow rate of air flowing in the air supply passage,
A rotation speed detecting means for detecting the engine speed, an idle speed control valve opening detecting means for detecting the idle speed control valve opening during engine idle operation, and the idle speed control valve opening having a predetermined value When the engine speed is equal to or less than the second predetermined value which is higher than the first predetermined value, and a rotation speed increase suppressing means for suppressing an increase in the engine speed is provided. Internal combustion engine.