JPH0645644Y2 - Fuel injection valve diagnostic device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a fuel injection valve diagnostic device for diagnosing an abnormality of a fuel injection valve provided for each cylinder in an engine intake passage.

<Prior Art> In an electronically controlled fuel injection device for an internal combustion engine, an electromagnetic fuel injection valve is provided for each cylinder in an engine intake passage, and a fuel is supplied by a drive pulse signal from a control unit to open the fuel. Is being supplied by injection.

To control the fuel injection amount, the basic fuel injection amount is set based on the state quantity of intake air, while the air-fuel ratio feedback correction coefficient and the learning correction coefficient are set based on the signal from the O ₂ sensor. The correction is performed to set the final fuel injection amount, and a drive pulse signal having a pulse width corresponding to the final fuel injection amount is given to the fuel injection valve at the set timing.

There is also a system in which correction amounts such as an air-fuel ratio feedback correction coefficient and a learning correction coefficient are set for each cylinder (see Japanese Patent Application No. 62-297744).

<Problems to be Solved by the Invention> By the way, when an abnormality occurs in the fuel injection valve, it is necessary to promptly detect it and give an alarm.

However, conventionally, leak diagnosis of the fuel injection valve has been performed, but no device for diagnosing the leak has been proposed.

In view of such circumstances, an object of the present invention is to provide a fuel injection valve diagnostic device capable of diagnosing an abnormality including clogging of a fuel injection valve.

<Means for Solving the Problem> Therefore, the present invention is an internal combustion engine having a fuel injection valve for each cylinder in the engine intake passage, and as shown in FIG.
Basic fuel injection amount setting means for setting the basic fuel injection amount based on the state quantity of intake air, and cylinder-specific fuel injection amount for correcting the basic fuel injection amount for each cylinder with a cylinder-specific correction amount Setting means, cylinder-by-cylinder fuel injection control means for operating the fuel injection valve at a fuel injection amount set for each cylinder, cylinder-by-cylinder air-fuel ratio detection means for detecting an air-fuel ratio for each cylinder, and detection for each cylinder A cylinder-by-cylinder correction amount setting means for increasing or decreasing the cylinder-by-cylinder correction amount according to the air-fuel ratio, and comparing the cylinder-by-cylinder correction amount of each cylinder with the cylinder-by-cylinder correction amount of other cylinders, A fuel injection valve diagnostic device is provided with a fuel injection valve abnormality determination means that determines that the fuel injection valve is abnormal when the difference between them is large.

<Operation> In the above configuration, when the cylinder-by-cylinder correction amount of one cylinder changes more than the cylinder-by-cylinder correction amount of another cylinder, it is determined that the fuel injection valve is clogged.

This is because when the fuel injection valve of a certain cylinder is clogged, the air-fuel mixture in that cylinder is diluted, and as a result, the cylinder-by-cylinder correction amount for that cylinder changes significantly for increasing correction.

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

Referring to FIG. 2, in the intake passage 2 of the engine 1 (fourth-stage cylinder), electromagnetic fuel injection valves 11 to 14 are provided for each cylinder.
A drive pulse signal output for each cylinder from the control unit 3 with a built-in microcomputer is energized to open the valve, and fuel is injected and supplied.

A signal from the air flow meter 4 and a signal from the crank angle sensor 5 are input to the control unit 3.

Also, the exhaust passages 6A and 6B have # 1 cylinders, # 4 cylinders, and # 2 cylinders.
The exhaust gas is collected in each of two cylinder groups of the cylinder and the # 3 cylinder (cylinders whose exhaust strokes are not close to each other are grouped), and the exhaust gas is guided to the three-way catalyst 7.
O ₂ sensors 8A and 8B are provided at the exhaust collecting portions of the corner exhaust passages 6A and 6B or at their downstream sides, respectively. These O ₂
The sensors 8A and 8B are for detecting the air-fuel ratio of the air-fuel mixture sucked into each cylinder of the engine 1 via the O ₂ concentration in the exhaust gas, and the output thereof is input to the control unit 3.

The control of the fuel injection amount is performed by the microcomputer in the control unit 3 according to the flowcharts of FIGS.

FIG. 3 is a fuel injection control routine.

In step 1 (indicated as S1 in the figure, and so on)
As a parameter indicating the state quantity of the intake air, the intake air flow rate Q is detected based on the signal from the air flow meter 4, and the engine speed N is detected based on the signal from the crank angle sensor 5.

In step 2, the basic fuel injection amount Tp = K · Q / N (K is a constant) is calculated from the intake air flow rate Q and the engine speed N. This portion corresponds to the basic fuel injection amount setting means.

In step 3, it is determined which cylinder is the cylinder to be injected in the intake stroke, and the process branches based on this. still,
In the following, the case where this is the # 1 cylinder and the process proceeds to step 4 will be described.

In step 4, the cylinder-by-cylinder air-fuel ratio feedback correction coefficient F ₁ for the # 1 cylinder and the cylinder-by-cylinder learning correction coefficient L ₁ for the # 1 cylinder, which are set by the correction amount setting routine described later, are read. However, the learning correction coefficient for each cylinder is for each area where the engine is operating.

In step 5, the fuel injection Ti is calculated according to the following equation. This portion corresponds to the cylinder fuel injection amount setting means.

Ti = Tp · (1 + F ₁ + L ₁ ) In step 6, a drive pulse signal having a pulse width corresponding to Ti is output to the fuel injection valve 11 of the # 1 cylinder at a predetermined timing to perform fuel injection. This portion corresponds to cylinder-by-cylinder fuel injection control means.

FIG. 4 shows a correction amount setting routine.

In step 11, it is determined which cylinder is in the exhaust stroke, and the process branches based on this. In the following, the case where this is the # 1 cylinder and the process proceeds to step 12 will be described.

In step 12, the correction amount setting subroutine (# 1-SUB) for the # 1 cylinder shown in FIG. 5 is executed.

The correction amount setting subroutine for the # 1 cylinder in FIG. 5 will be described.

In step 21, the output voltage of the O ₂ sensor 8A is read.

In step 22, the output voltage is compared with the slice level voltage to determine rich / lean of the air-fuel ratio.

In the case of rich, the routine proceeds to step 23, where the cylinder-by-cylinder air-fuel ratio feedback correction coefficient F ₁ is decreased by a predetermined value ΔF.

In the case of lean, the routine proceeds to step 24, where the cylinder-by-cylinder air-fuel ratio feedback correction coefficient F ₁ is increased by a predetermined value ΔF.

In step 25, it is determined whether or not the learning condition is predetermined.

In the case of the predetermined learning condition, the process proceeds to step 26, and as shown in the following equation, the predetermined ratio of the cylinder-by-cylinder air-fuel ratio feedback correction coefficient F ₁ is added to the cylinder-by-cylinder learning correction coefficient L ₁ , and the cylinder-by-cylinder learning correction coefficient Update L ₁ . However, the learning correction coefficient is set / updated for each area of the engine operating state.

L ₁ ← L ₁ + F ₁ / M (M is a constant) Here, the step 21 corresponds to the cylinder-by-cylinder air-fuel ratio detecting means, and the steps 22 to 26 correspond to the cylinder-by-cylinder correction amount setting means.

The fuel injection valve diagnostic device according to the present invention is configured and used as described above for the cylinder-specific correction amount α ₁ = F ₁ + L _{1 to} α _4.
= F ₄ + L ₄ are compared with each other,
The judgment of 1) is made.

This determination is performed by the microcomputer according to the flowchart of FIG. 6, and this corresponds to the fuel injection valve, that is, the determination means.

In step 31, it is determined whether or not the condition is the diagnosis condition.

Here, the diagnostic condition means, for example, that the engine speed N is 2000 rp.
If the water temperature is less than m and the water temperature is more than 75 ° C, the diagnosis is not performed otherwise. This is done because in the high rotation range or the low temperature range, cylinder discrimination becomes difficult due to the limit of the response performance of the O ₂ sensor, and the purpose of diagnosis cannot be achieved.

In step 32, the cylinder correction amounts α _{1 to} α ₄ are sampled. Here, α _{1 to} α ₄ are represented by the following formulas.

α ₁ = F ₁ + L ₁ , α ₂ = F ₂ + L ₂ α ₃ = F ₃ + L ₃ , α ₄ = F ₄ + L ₄ Then, in step 33, whether a predetermined time has passed (or a predetermined sampling number has ended) Is judged, and if not, sampling is continued.

When the predetermined time has elapsed, the process proceeds to step 34.

In step 34, the sampled cylinder-by-cylinder correction amount α ₁
Average values ₁ to ₄ of α ₄ are obtained.

Next, in step 35, regarding the fuel injection valve of the # 1 cylinder,
The judgment is made by making the following comparisons. ₁ : ( ₂ + ₃ + ₄ ) / 3 When these differences are large (substantially ₁ is larger than a predetermined value), the routine proceeds to step 36, where it is determined that the # 1 cylinder fuel injection valve is blocked. Then, an appropriate flag is set so that an alarm can be issued.

The reason why such a diagnosis can be made is that when the fuel injection valve of the # 1 cylinder is clogged, the air-fuel mixture of the # 1 cylinder is diluted, and as a result, the correction amount α for each cylinder corresponding to the # 1 cylinder is
_{This is because 1} (= F ₁ + L ₁ ) becomes a large value due to the increase correction.

Next, proceeding to step 37 and thereafter, if the fuel injection valves of the # 2, # 3, and # 4 cylinders are similarly compared with the following,
That is, the determination can be made. ₂ :( ₁ + ₃ + ₄ ) / 3 ₃ :( ₁ + ₂ + ₄ ) / 3 ₄ :( ₁ + ₂ + ₃ ) / 3 <Effect of device> As described above, according to the present invention, the fuel is used. By using the cylinder-by-cylinder correction amount that is set in the cylinder-by-cylinder control of the injection amount, it is possible to determine abnormalities including clogging of the fuel injection valve, improve the accuracy of fuel injection valve diagnosis, and only by adding software. It is possible and highly practical.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing a configuration of a fuel injection valve diagnostic device according to the present invention, FIG. 2 is a system diagram showing an embodiment of the present invention, and FIGS. 3 to 5 are flowcharts of fuel injection control, FIG. 6 is a flowchart of the fuel injection valve diagnosis. 1 ... Engine, 2 ... Intake passage, 3 ... Control unit,
4 ... Air flow meter, 5 ... Crank angle sensor, 6A, 6B
… Exhaust passage, 8A, 8B… O ₂ sensor, 11 to 14… Fuel injection valve

Claims (1)

[Scope of utility model registration request] 1. An internal combustion engine having a fuel injection valve for each cylinder in an engine intake passage, comprising basic fuel injection amount setting means for setting a basic fuel injection amount based on a state quantity of intake air, and basic for each cylinder. Cylinder fuel injection amount setting means for correcting the fuel injection amount by the cylinder correction amount and setting the fuel injection amount, and cylinder-specific fuel injection control means for operating the fuel injection valve with the fuel injection amount set for each cylinder. And a cylinder-by-cylinder air-fuel ratio detecting means for detecting the air-fuel ratio for each cylinder, and a cylinder-by-cylinder correction amount setting means for setting the cylinder-by-cylinder correction amount to increase or decrease according to the air-fuel ratio detected for each cylinder. In the above, the cylinder-by-cylinder correction amount of each cylinder is compared with the cylinder-by-cylinder correction amounts of other cylinders, and a fuel injection valve abnormality determination means for determining a fuel injection valve abnormality when these differences are large is provided. Fuel injection valve diagnosis Location.