JPH059470Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to an electronically controlled fuel injection device for an internal combustion engine, and in particular, the intake air flow rate is set based on the detected values of the throttle valve opening and the engine rotational speed. The present invention relates to an electronically controlled fuel injection device configured to set a fuel injection amount based on an intake air flow rate.

<Prior art> Conventionally, this type of electronically controlled fuel injection device
For example, there is something like the one shown in Figure 5.
-Refer to No. 008127, etc.).

A throttle valve opening sensor 4 for detecting the opening degree α of a throttle valve 3 interposed in the intake passage 2 of the internal combustion engine 1, and a rotation speed sensor 5 such as a crank angle sensor for detecting the engine rotation speed N are provided. , the detection signals from these sensors 4 and 5 are input to the control unit 6. The ROM of the microcomputer built in the control unit 6 stores the intake air flow rate Q corresponding to each of a plurality of operating regions divided using the throttle valve opening α and the engine speed N as parameters. Data is stored, and based on the detected values of throttle valve opening α and engine rotational speed N, data on the intake air flow rate Q in the corresponding operating region is searched from the data.

Then, the basic fuel injection amount Tp (=K×Q/N; K is a constant) is calculated based on the retrieved intake air flow rate Q and the engine rotational speed N detected by the rotational speed sensor 5, and Various correction coefficients COEF according to engine operating conditions such as engine cooling water temperature, air-fuel ratio feedback correction coefficient β, and correction amount Ts for correcting changes in effective valve opening time of electromagnetic fuel injection valve 7 due to battery voltage. The basic fuel injection amount Tp is corrected by these calculations to calculate the final fuel injection amount Ti (=Tp×COEF×β+Ts).

When the fuel injection amount Ti is set, an injection pulse signal with a pulse width corresponding to the fuel injection amount Ti is output to the fuel injection valve 7, thereby causing the engine 1 to inject and supply a predetermined amount of fuel. There is also a system that stores data on the basic fuel injection amount Tp corresponding to each of a plurality of operating ranges that are divided using the throttle valve opening α and the engine rotational speed N as parameters.

However, if the fuel injection amount Ti is set based on the intake air flow rate Q that is retrieved based on the detected values of the throttle valve opening degree α and the engine rotational speed N as described above, or If the fuel injection amount Ti is set based on the basic fuel injection amount Tp that is retrieved based on the detected values of degree α and engine rotational speed N, the air that is supplied bypassing the throttle valve is Since this has no relation to the setting of the fuel injection amount, there is a risk that the fuel injection amount will be set to match the intake air flow rate which is smaller than the actual intake air flow rate, causing the air-fuel ratio to become over-lean.

That is, an on-off valve is interposed in the bypass intake passage that bypasses the throttle valve, and this on-off valve is controlled to open, for example, when the electrical load increases during engine idling, thereby opening the bypass intake passage and increasing the amount of air. When air that is not related to the throttle valve opening α is supplied, such as when There is a shortage of fuel corresponding to the amount of air that is supplied bypassing the throttle valve.

For this reason, in the past, the on-off valve that opens and closes the bypass intake passage was turned on and off (drive signal turned on and off).
The intake air flow rate Q retrieved by is corrected to increase by a predetermined amount. That is, when controlling idle rotation by opening and closing the bypass intake passage, the negative pressure in the intake passage is large and the airflow flowing through the bypass intake passage becomes a sonic flow, so the flow rate is approximately constant depending on the area of the passage. Become. Therefore, for example, when the normally closed electromagnetic on-off valve is in the on state and the bypass intake passage is controlled to be opened, the retrieved intake air flow rate Q is increased by a predetermined amount (the air flow rate corresponding to the passage area of the bypass intake passage). By setting the fuel injection amount Ti based on the air flow rate plus the air flow rate, the air-fuel ratio can be controlled to a level that does not cause problems.

An example of such control will be briefly explained based on the flowchart (Ti calculation routine) in FIG. The rotational speed N is input, and in step 22, data on the intake air flow rate Q is retrieved from a three-dimensional map of α-N-Q based on these detected values.

In step 23, the normally closed electromagnetic on-off valve that opens and closes the bypass intake passage that bypasses the throttle valve is set on and off. When it is on and the bypass intake passage is controlled to open, the next step 24 is set. Proceeding to step 22, a predetermined intake air flow rate Q ₀ (intake air flow rate for the bypass intake passage) is added to the intake air flow rate Q retrieved in step 22, and the result is set as the final intake air flow rate Q.

Then, in step 25, the basic fuel injection amount Tp is calculated based on the intake air flow rate Q to which the predetermined intake air flow rate _Q0 has been added, and in step 26, this basic fuel injection amount Tp is calculated using various correction coefficients such as COEF. A correction calculation is performed to set the final fuel injection amount Ti.

On the other hand, when the electromagnetic on-off valve is off and the bypass intake passage is controlled to be closed, step 24 is jumped and the process proceeds to step 25. Therefore, when the electromagnetic on-off valve is off, the final fuel injection amount Ti is determined based on the intake air flow rate Q retrieved in step 22.
will be set.

<Problem to be solved by the invention> However, when the intake air flow rate is increased and corrected based on the on/off status of the on-off valve that opens and closes the bypass intake passage, the valve body of the on-off valve becomes stuck. Even if the bypass intake passage remains closed even if the on-off valve is turned on (open control) due to a break in the drive circuit or a break in the drive circuit, the intake air flow rate will be increased. . Therefore, when such an on-off valve fails, the intake air flow rate used to set the fuel injection amount becomes larger than the actual intake air flow rate by the amount of the correction increase, resulting in an overrich air-fuel ratio and a drop in rotational speed. There was a fear that this would occur.

The present invention was devised in view of the above problems, and is an electronically controlled fuel injection system that can prevent the air-fuel ratio from becoming overrich by increasing the fuel injection amount when an abnormality occurs in the on-off valve that opens and closes the bypass intake passage. I will provide a.

<Means for solving the problem> Therefore, in the present invention, as shown in FIG. An engine rotation speed detection means for detecting the rotation speed, and an intake air flow rate in the relevant operating state based on the detected values of the throttle valve opening degree and the engine rotation speed, and a fuel injection amount is set based on the intake air flow rate. a fuel injection amount setting means; a bypass intake passage opening/closing control detecting means for detecting opening/closing control of an opening/closing valve that opens/closes a bypass intake passage that bypasses the throttle valve; and a bypass intake passage opening/closing control detecting means for controlling opening of the opening/closing valve. fuel injection amount correction setting means for increasing and setting the fuel injection amount set by the fuel injection amount setting means by a predetermined amount when the condition is detected; In an electronically controlled fuel injection device for an internal combustion engine, the electronically controlled fuel injection device for an internal combustion engine is provided with: a fuel injection valve drive control means for driving and controlling a fuel injection valve; an on-off valve abnormality determination means that determines whether the on-off valve is abnormal when the rotational speed detection means detects that the engine rotation speed has decreased to a predetermined level or more; Further, there is provided an increase correction setting prohibition means for prohibiting the increase correction setting of the fuel injection amount by the fuel injection amount correction setting means when an abnormality is determined.

<Operation> According to the electronically controlled fuel injection device having such a configuration,
When the opening degree of the throttle valve and the engine rotational speed are detected, the intake air flow rate in the relevant operating state is set based on these detected values, and the fuel injection amount is thereby set. Additionally, when the opening/closing valve that opens and closes the bypass intake passage that bypasses the throttle valve is controlled to open, the fuel injection amount is increased by an amount corresponding to the amount of air supplied through the bypass intake passage. .

On the other hand, if it is detected that the engine rotational speed has decreased by more than a predetermined value as a result of the opening control of the on-off valve and the fuel increase correction corresponding to the amount of bypass air, it is determined that the on-off valve is abnormal and the bypass air is increased. Prohibits fuel increase correction corresponding to the amount, and sets a normal fuel injection amount that does not include the amount equivalent to the bypass air amount.

<Example> An example of the present invention will be described below based on the drawings.

FIG. 2 shows the hardware configuration of this embodiment. Incidentally, the same elements as those in the conventional example shown in FIG. 5 are given the same reference numerals, and the explanation thereof will be omitted.

The control unit 6 has an opening α of the throttle valve 3 detected by a throttle valve opening sensor 4 as a throttle valve opening detection means, and a rotation speed sensor 5 as an engine rotation speed detection means. engine rotational speed N and exhaust passage 1
The oxygen concentration in the exhaust gas, which is closely related to the air-fuel ratio of the engine intake air-fuel mixture, detected by the oxygen concentration sensor 10 installed in the engine 1, and the oxygen concentration in the engine cooling jacket, which is detected by the water temperature sensor 12. cooling water temperature
Tw is now entered. Also,
The control unit 6 controls the opening and closing of a normally closed electromagnetic on-off valve 9 and an electromagnetic fuel injection valve 7, which open and close a bypass intake passage 8 provided by bypassing the throttle valve 3, respectively, by controlling energization.

That is, the control unit 6 also functions as a fuel injection amount setting means, a fuel injection valve drive control means, a bypass intake passage opening/closing control detection means, a fuel injection amount correction setting means, an on/off valve abnormality determination means, and an increase correction setting prohibition means. be.

The operation of the electronically controlled fuel injection system having such a configuration will be explained based on the flowcharts shown in FIGS. 3 and 4.

The flowchart in Fig. 3 is a routine for setting the fuel injection amount Ti, and in step 1 (indicated as "S" in the figure, the same shall apply hereinafter), the throttle valve opening α, engine rotational speed N, cooling water temperature, Input various signals such as Tw, and in step 2, step 1
Based on the detected values of the throttle valve opening α and the engine rotational speed N input in the ROM of the microcomputer built in the control unit 6.
Data on the intake air flow rate Q corresponding to the operating state is retrieved from the α-N-Q three-dimensional map stored in advance.

In step 3, it is determined whether the normally closed electromagnetic on-off valve 9 that opens and closes the bypass intake passage 8 that bypasses the throttle valve 3 is on or off (the drive signal output is on or off).
When the opening control is being performed, the process proceeds to the next step 4, and it is determined whether or not a _Q0 addition prohibition instruction, which will be described later, has been issued.If the prohibition instruction has not been issued, the process proceeds to step 5. The control unit 6 controls the opening/closing of the electromagnetic on-off valve 9 by detecting an increase in electrical load or the like.

In step 5, a predetermined intake air flow rate Q ₀ (intake air flow rate for 8 bypass intake passages) is added to the intake air flow rate Q retrieved in step 2, and the result is set as the final intake air flow rate Q.

On the other hand, when it is determined in step 3 that the electromagnetic on-off valve 9 is OFF and control is being performed to close the bypass intake passage 8, and when it is determined in step 4 that the Q ₀ addition prohibition instruction has been issued, step 5 is executed. Jump to step 6. That is, when the electromagnetic on-off valve 9 is OFF and when the _Q0 addition prohibition instruction is issued even when it is ON, the basic fuel injection amount Tp is calculated based on the intake air flow rate Q searched in step 2. , when the electromagnetic on-off valve 9 is ON and the _Q0 addition prohibition instruction has not been issued, the basic fuel injection amount Tp is obtained by adding the bypass air amount _Q0 to the intake air flow rate Q searched in step 2.
The calculations are as follows.

In step 6, the basic fuel injection amount Tp ((=K×Q/ _N ; K is constant).

Then, in step 7, various correction coefficients COEF, which are mainly set based on the cooling water temperature Tw, an air-fuel ratio feedback correction coefficient β (clamped in the engine idling operating state), which is set based on the oxygen concentration in the exhaust gas, and the battery A correction amount Ts is set to correct the change in the effective valve opening time of the fuel injection valve 7 due to the voltage of
The basic fuel injection amount Tp calculated in is corrected to obtain the final fuel injection amount Ti (=Tp×COEF×β+Ts)
Set.

The Q ₀ addition prohibition instruction described above is performed according to the Q ₀ addition (increase correction setting) prohibition instruction routine shown in the flowchart of FIG. Note that this routine is performed when the engine is in idle operation and the cooling water temperature Tw
is executed when the temperature is completely warmed up to a predetermined level or higher.

In step 11, the solenoid on/off valve 9 is turned ON/OFF.
(ON/OFF of the drive signal) is determined, and if the electromagnetic on-off valve 9 is ON and the bypass intake passage 8 is controlled to be opened, the process proceeds to step 12, and the electromagnetic on-off valve 9 is OFF and the bypass intake passage 8 is controlled to be opened. When the passage 8 is controlled to be closed, it is returned as is.

In step 12, it is determined whether the electromagnetic on-off valve 9 was turned off a predetermined time ago. This is to determine the Q ₀ addition prohibition instruction based on the rotation speed fluctuation immediately after the electromagnetic on-off valve 9 is turned on.

Here, before the predetermined time, the electromagnetic on-off valve 9
If it is determined that the
Proceed to step 13, and after turning on the electromagnetic on-off valve 9, it is determined whether or not the engine has stalled. Further, if it is determined that the electromagnetic on-off valve 9 was not OFF before a predetermined time, that is, if more than a predetermined time has elapsed since it was turned ON, the control is returned directly.

When it is determined in step 13 that an engine stall has occurred,
Proceed to step 15 and instruct _Q0 addition to be prohibited. This is because the electromagnetic on-off valve 9 was turned on, so when the basic fuel injection amount Tp was calculated by adding the bypass air amount Q ₀ , it was actually determined that the electromagnetic on-off valve 9 was malfunctioning (the valve body was stuck or the drive circuit was disconnected). ), which caused the bypass intake passage 8 to remain closed, causing the air-fuel ratio to become overrich and causing the engine stall.

On the other hand, if it is determined in step 13 that engine stalling has not occurred, the process proceeds to step 14, where it is determined whether the rotational speed N is decreasing at a rate greater than a predetermined rate. Here, when it is determined that the rotational speed has decreased by more than a predetermined value, it is determined that the bypass intake passage 8 is not opened due to a failure of the electromagnetic on-off valve 9 and the air-fuel ratio has become overrich, even if the engine has not stalled. Then, the process proceeds to step 15, where a _Q0 addition prohibition instruction is issued. On the other hand, in step 14, the rotational speed N
When it is determined that Q0 has not decreased beyond a predetermined level, it is assumed that the electromagnetic on-off valve 9 is operating normally and the bypass intake passage 8 is opened, and the _Q0 addition prohibition instruction is not issued. Make it return.

When the Q ₀ addition prohibition instruction is issued in step 15,
In step 4 of the fuel injection amount calculation routine shown in the flowchart of FIG. 3, the _Q0 addition prohibition instruction is determined, and for example, the electromagnetic on-off valve 9 is turned on (opening control).
Do not increase the amount of fuel for bypass air even when Therefore, if the electromagnetic on-off valve 9 does not open even if it is controlled to open due to a stuck valve body or a disconnection in the drive circuit, the fuel injection amount Ti should be set in consideration of the amount of bypass air. Rotational speed N
This is determined based on the drop in the fuel injection amount Ti, and the fuel injection amount Ti is not increased even if the electromagnetic on-off valve 9 is controlled to open from the next time onwards, thereby preventing the air-fuel ratio from becoming overrich.

The above-mentioned Q ₀ addition (fuel increase correction setting for bypass air amount) prohibition instruction is configured to be canceled when a predetermined time has elapsed from the prohibition judgment or when the battery is removed. The history of instructions for prohibiting ₀ addition may be stored.

<Effects of the invention> As explained above, according to the invention, when there is an abnormality in the on-off valve that opens and closes the bypass intake passage that bypasses the throttle valve (when it is actually closed due to open control)
Another advantage is that the fuel injection amount is corrected to increase by the amount of bypass air, thereby preventing the air-fuel ratio from becoming overrich, and preventing a drop in rotational speed and engine stalling.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of the present invention, Fig. 2 is a system diagram showing an embodiment of an electronically controlled fuel injection device for an internal combustion engine according to the invention, and Fig. 3 shows a fuel injection amount calculation routine in the same embodiment. flowchart,
Fig. 4 is a flowchart showing the increase correction setting prohibition instruction routine in the same embodiment as above, Fig. 5 is a system diagram showing an example of a conventional electronically controlled fuel injection device, and Fig. 6 is a conventional increase in fuel injection amount using bypass air. 7 is a flowchart showing correction control. DESCRIPTION OF SYMBOLS 1... Engine, 2... Intake passage, 3... Throttle valve, 4... Throttle valve opening sensor, 5... Rotational speed sensor, 6... Control unit, 7
...Fuel injection valve, 8...Bypass intake passage, 9...
...Solenoid on-off valve.

Claims (1)

[Scope of utility model registration request] Throttle valve opening detection means for detecting the opening of a throttle valve installed in an intake passage of the engine; engine rotation speed detection means for detecting the rotation speed of the engine;
a fuel injection amount setting means that sets an intake air flow rate in the operating state based on detected values of the throttle valve opening degree and engine rotational speed, and sets a fuel injection amount based on the intake air flow rate; and a fuel injection amount setting means that bypasses the throttle valve. bypass intake passage opening/closing control detection means for detecting the opening/closing control of the opening/closing valve that opens and closes the bypass intake passage; and when the opening control state of the opening/closing valve is detected by the bypass intake passage opening/closing control detection means, the fuel injection amount is determined. a fuel injection amount correction setting means for increasing the fuel injection amount set by the setting means by a predetermined amount; and a fuel injection valve drive control for driving and controlling the fuel injection valve according to the set fuel injection amount. In the electronically controlled fuel injection device for an internal combustion engine, the engine rotation speed is set to a predetermined value by the engine rotation speed detection means when the opening control of the on-off valve is detected by the bypass intake passage opening/closing control detection means. On-off valve abnormality determining means that determines whether the on-off valve is abnormal when it is detected that the on-off valve has decreased above the above level;
and an increase correction setting prohibition means for prohibiting the fuel injection amount correction setting means from setting an increase in the fuel injection amount when the on-off valve abnormality determination means determines that the on-off valve is abnormal. An electronically controlled fuel injection system for internal combustion engines.