JPH04350358A - Fuel leak self-diagnostic device for electronically controlled fuel injection type internal combustion engine - Google Patents

Abstract

PURPOSE:To self-diagnose fuel leak from a fuel injection valve accurately without being influenced by the characteristic dispersion of an intake air quantity detecting means. CONSTITUTION:A fuel pressure sensor 8 is provided between a fuel injection valve 2 and a pressure regulator 4 so as to detect fuel pressure at the driving time of a fuel pump 3 after the stop of an engine and to detect fuel pressure upon the lapse of the specified time or more after the stop of the fuel pump 3. When the fuel pressure difference is more than the specified value, fuel leak is judged by a judging means 9, and an alarm means 10 is put into action. The fuel leak from the fuel injection valve 2 can be thereby self-diagnosed accurately without being influenced by the dispersion of an intake air quantity detecting means.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel leak self-diagnosis device for an electronically controlled fuel injection type internal combustion engine that can self-diagnose fuel leaks in an internal combustion engine having an electronically controlled fuel injection device.

0002

2. Description of the Related Art A conventional fuel leak self-diagnosis device, as described in, for example, Japanese Patent Laid-Open No. 63-65155, adjusts the fuel injection amount to a reference injection amount that is uniquely determined by the operating state of the engine. Corrected with the air-fuel ratio correction value calculated from the fuel ratio feedback correction coefficient and learning correction coefficient,
In a device that controls fuel, fuel leaks from the fuel supply valve when the amount of change in the steady value of the learning correction coefficient in a region with a small intake air amount is larger than the steady value of the learning correction coefficient in a region with a large intake air amount. I try to diagnose if it is.

0003

[Problems to be Solved by the Invention] In the conventional fuel leak self-diagnosis device, variations in the characteristics of the intake air amount detection means,
If the intake air amount detection error is large due to changes over time, etc., there is a problem in that a fuel leak may be diagnosed even when no fuel leak actually occurs.

The present invention has been made to solve the above-mentioned problems, and is capable of accurately and automatically detecting fuel leakage from a fuel injection valve without being affected by variations in the characteristics of the intake air amount detection means. The object of the present invention is to obtain a fuel leak self-diagnosis device for an electronically controlled fuel injection type internal combustion engine that can perform diagnosis.

[0005]

[Means for Solving the Problems] A fuel leak self-diagnosis device for an electronically controlled fuel injection type internal combustion engine according to the present invention is provided when the fuel pressure after the fuel pump is stopped exceeds a predetermined value with respect to the fuel pressure when the fuel pump is driven. The fuel injection valve is provided with a determination means for determining that the fuel injection valve is leaking when the engine key is input or when the fuel pressure after the engine key is input and before the engine is started exceeds a predetermined value.

[0006]

[Operation] The determination means in this invention determines whether the fuel pressure when the fuel pump is running changes when the fuel pressure after the fuel pump is stopped changes to a predetermined value or more, or after the engine key is input and before the engine starts. When the difference between the fuel pressure of the fuel pump and the fuel pressure when the fuel pump is stopped exceeds a predetermined value, a fuel leak self-diagnosis is performed to determine that the fuel injection valve is leaking.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the fuel leak self-diagnosis device for an electronically controlled fuel injection type internal combustion engine according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of one embodiment, and FIG. 2 is a system configuration diagram of an electronically controlled fuel injection type internal combustion engine to which the embodiment of FIG. 1 is applied.

In both FIGS. 1 and 2, the same parts will be described with the same reference numerals. First, in FIG. 2, air is supplied to the cylinders of an internal combustion engine through an intake pipe 12, and the amount of intake air in this intake pipe 12 is detected by an air flow sensor 11. It looks like this. The detection output of this air flow sensor 11 is output to an electronic control circuit 18.

[0009] Furthermore, 13 is a distributor;
The rotor of the distributor 13 is driven to rotate at half the rotation speed of the internal combustion engine, and a rotation sensor 14 that outputs the engine speed is disposed inside. The detection output of the rotation sensor 14 is output to an electronic control circuit 18.

The internal combustion engine is provided with a thermistor-type engine cooling water temperature sensor 15 for detecting the engine cooling water temperature. The detection output of the engine coolant temperature sensor 15 is also output to the electronic control circuit 18.

Further, an electromagnetically actuated fuel injection valve 2 is provided near each cylinder intake port of the intake pipe 12. The fuel injection valve 12 is connected to a delivery pipe 17, and the delivery pipe 17 is connected to the fuel pump 3.

The fuel pump 3 pumps up fuel from a fuel tank 16 and supplies the fuel to the fuel injection valve 2 through a delivery pipe 17.

The fuel pressure within the delivery pipe 17 is regulated by a pressure regulator 4, which serves as a fuel pressure regulating valve. The pressure regulator 4 regulates the fuel pressure in the delivery pipe 17 so that the fuel pressure applied to the fuel injection valve 2 does not exceed a predetermined value relative to the pressure in the intake pipe 12.

A fuel pressure sensor 8 is provided in the delivery pipe 17 to detect the fuel pressure within the delivery pipe 17. The detection output of the fuel pressure sensor 8 is output to a control circuit 18. This fuel pressure sensor 8 is constituted by a semiconductor pressure sensor.

The electronic control circuit 18 is connected to the positive terminal of the battery 21 via an engine key switch 19.
The negative electrode of this battery 21 is grounded. An alarm lamp 20 is connected to the control circuit 18 .

The electronic control circuit 18 is connected to the air flow sensor 11
, the detection signals from the rotation sensor 14, the engine cooling water temperature sensor 15, and the engine key switch 19, and based on these detection data, calculate the fuel injection amount, control the opening time of the fuel injection valve 2, and The fuel ratio is controlled.

The warning lamp 20 is turned on by the electronic control circuit 18 when the fuel injection valve 2 is leaking fuel, to warn the user of the fuel leak.

The battery 21 is designed to supply backup power for memory storage in the electronic control circuit 18 even when the engine key switch 19 is off.

Next, FIG. 1 will be described. In FIG. 11, as already mentioned, the same parts as in FIG. 2 are given the same reference numerals and will not be described again here. In FIG. 1, a cylinder 1 of an internal combustion engine, a fuel injection valve 2,
The fuel pump 3, pressure regulator 4, and fuel pressure sensor 8 are the same as in FIG. 2, and the alarm means 10 corresponds to the alarm lamp 20 in FIG.

The control means 5 corresponds to the electronic control circuit 18 shown in FIG. 2, and the storage means 6 and the determination means 9 are built in the electronic control circuit 18.

The operating state detection means 7 includes the air flow sensor 11, rotation sensor 14, and engine cooling water temperature sensor 1 shown in FIG.
5, etc.

Next, the internal configuration of the electronic control circuit 18 will be explained. FIG. 3 is a block diagram showing its configuration,
As is clear from FIG. 3, the electronic control circuit 18 is mainly composed of a one-chip microcomputer 100.

That is, a CPU 200, a counter 201, and a timer 20 perform arithmetic processing according to a predetermined program.
2. A/D (analog/digital) converter 203, input port 24, ROM 205, RAM 206, and output port 207 are each connected to common bus 208, and the configuration is such that necessary data transfer is performed according to instructions from CPU 200. There is.

On the other hand, the ignition signal from the rotation sensor 14 shown in FIG. It has become.

Each time this interrupt is applied to the microcomputer 100, the CPU 200 reads the value of the counter 201, calculates the number of cycles from the difference from the previous value, and based on this, the microcomputer 100 adjusts the engine rotation. Calculate speed.

A second input interface circuit 102 included in the electronic control circuit 18 inputs the analog detection outputs of the air flow sensor 11, engine coolant temperature sensor 15, and fuel pressure sensor 8, and sends them to the A/D converter 203. Forward.

The level of the engine key switch 19 is converted into a digital signal level by the third input interface circuit 103 in the electronic control circuit 18 and is input to the input port 204 .

Further, a pulse corresponding to the fuel injection amount calculated by the microcomputer 100 is outputted to the fuel injection valve 2 from the output port 207 through the output interface circuit 104, and a fuel pump drive signal is outputted from the output port 207 to the output interface circuit 104. It is designed to be outputted to the fuel pump 3 through a circuit 104.

The signal output from the output port 207 to the output interface circuit 104 is amplified by the output interface circuit 104 so that it becomes a signal sufficient to drive the fuel pump 3 and the fuel injection valve 2.

Furthermore, a first power supply circuit 105 and a second power supply circuit 106 are provided within the electronic control circuit 18, respectively. Even if the engine key switch 19 is turned off, the first power supply circuit 105 continues to operate the microcomputer 1 within a certain period of time even if the engine key switch 19 is turned off.
00 is energized, it receives a control signal from the output port 207.

The second power supply circuit 106 supplies power to the RAM 206 so that data can be retained in the RAM 206 even when the engine key switch 19 is off.

Next, the fuel leak self-diagnosis routine, whose operation will be explained along the flowchart of FIG. 4, is performed for each main routine.

First, in step S10, it is determined whether the engine key switch 19 is on or off. As a result of this determination, if the engine key switch 19 is on, the process jumps to step S21 from the NO side of step S10, and if it is off, the process proceeds from the YES side of step S10 to step S11.

If it is determined that the engine key switch 19 is off, in step S11, the electronic control circuit 18
As a result, the fuel injection valve 2 is stopped and the fuel pump 3 is driven.

Next, in step S12, it is determined whether the engine rotation speed is 0 or not. As a result of this judgment, if the engine rotation speed is not 0, the process returns to step S12, and if the engine rotation speed is 0, the process returns to step S12.
If the answer is YES, the process advances to step S13.

In this step S13, the fuel pressure PON when the fuel pump 3 is driven is detected by the fuel pressure sensor 8,
The detection output is stored in the RAM in the microcomputer 100.
206.

Next, the process proceeds to step S14, in which the driving of the fuel pump 8 is stopped, the timer 202 is set to an initial value, and the process proceeds to step S15.

In this step S15, step S14
The timer 202 initialized in step 1 waits until a predetermined time elapses. If the predetermined time has elapsed, step S
15, the process proceeds to step S16.

In step S16, the microcomputer 1 determines the fuel pressure POFF when the fuel pump 3 is stopped.
00 in the RAM 206, and the process advances to step S17.

In this step S17, the amount of change ΔP between the fuel pressure PON when the fuel pump 3 is driven and the fuel pressure POFF when the fuel pump 3 is stopped is calculated as ΔP=PON-POFF.
is calculated, and the process proceeds to step S18.

In this step S18, it is determined whether or not the amount of change ΔP in the fuel pressure is greater than a predetermined value γ, that is, ΔP
Determine ≧γ. As a result of this judgment, the amount of change in fuel pressure Δ
If P is larger than the predetermined value γ (ΔP≧γ), if the determining means 9 in FIG. 1 determines that there is a fuel leak in the fuel injection valve 2, the process proceeds from the YES side of step S18 to step S19 Data indicating that there is a fuel leak is stored in the RAM 206 within the microcomputer 100.

Further, as a result of the determination in step S18, if the amount of change ΔP in the fuel pressure is less than or equal to the predetermined value γ (ΔP≦γ), the process proceeds from the NO side of step S18 to step S20.
Proceed to.

In step S20, a signal is output to the output port 207 to stop the first power supply circuit 105. After this, power is no longer supplied to the electronic control circuit 18, and the CPU 200 stops.

At this time as well, the second power supply circuit 106
Power is supplied to M206, and the data indicating fuel leak is held until the next engine key switch 19 is turned on.

Next, when the engine key switch 19 is on, the routine proceeds to step S21 when the fuel leak self-diagnosis routine is entered. This step S21
Then, it is read whether or not there is a fuel leak, and if it is determined that there is a fuel leak, the process proceeds from the YES side of step S21 to step S22, the alarm lamp 20 is turned on, and the fuel leak self-diagnosis routine is ended.

Further, if it is determined in step S21 that there is no fuel leak, NO in step S21 is determined.
The fuel leak self-diagnosis routine ends immediately.

In the above embodiment, the fuel pressure when the fuel pump 3 is turned on or off is controlled by the engine key switch 19.
Although the measurement is performed after the engine is turned off, it is also possible to change the measurement so that the measurement is performed after the engine key switch 19 is turned on and before the engine is started.

FIG. 5 is a block diagram showing the configuration of the electronic control circuit 18 of the second embodiment, and as shown in FIG.
In the electronic control circuit 18, the engine key switch 1
9 directly turns on and off the first power supply circuit 105 without directly sending on and off information to the microcomputer 100, and the first power supply circuit 105 does not receive an output signal from the output port 207 of the microcomputer 100. It is composed of

Next, the operation will be explained along the flowchart of FIG. The fuel leak self-diagnosis routine is performed in the initialization routine of the microcomputer 100 after the engine key switch 19 is turned on. This must be done before starting the engine.

First, in step S101, the fuel pressure POFF when the fuel pump 3 is stopped is detected and stored in the RAM 206 in the microcomputer 100.

Next, the process advances to step S102, and the fuel pump 3 is driven. Next, proceed to step S103,
In step S103, the process waits for a period of time after the fuel pump 3 is driven until the fuel pressure within the delivery pipe 17 rises completely.

Thereafter, the process proceeds to step S104, where the fuel pressure PON when the fuel pump is driven is detected, and the process proceeds to the next step S104.
In 105, the difference ΔP between the fuel pressure PON when the fuel pump is driven and the fuel pressure POFF when the fuel pump is stopped, which is stored in the RAM 206 in step S101, is calculated.

In the next step S106, it is determined whether the difference ΔP is greater than or equal to a predetermined value γ, and as a result of this determination, ΔP
is greater than or equal to the predetermined value γ, the process branches from the YES side of step S106 to step S107, and this step S107
, if there is a fuel leak, the alarm lamp 20
lights up.

Furthermore, as a result of the determination in step S106, Δ
If P is less than or equal to the predetermined value γ, NO in step S106
The program branches to , completes the fuel leak self-diagnosis routine, and proceeds to the next initialization routine.

[0055]

As described above, according to the present invention, if the fuel pressure after the fuel pump stops changes by more than a predetermined value with respect to the fuel pressure when the fuel pump is driven, or after the engine key switch is input and before the engine starts, If the fuel pressure changes by a predetermined value or more, the determining means determines that there is a leak in the fuel injection valve, so there is an effect that a leak in the fuel system can be reliably determined.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a fuel leak self-diagnosis device for an electronically controlled fuel injection type internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a system configuration diagram of an electronically controlled fuel injection type internal combustion engine to which the above embodiment is applied.

FIG. 3 is a block diagram showing the internal configuration of an electronic control circuit in the electronically controlled fuel injection internal combustion engine of FIG. 2;

FIG. 4 is a flowchart showing the operation flow of the electronically controlled fuel injection type internal combustion engine of FIG. 2;

FIG. 5 is a block diagram showing the internal configuration of an electronic control circuit in another embodiment of the fuel leak self-diagnosis device for an electronically controlled fuel injection type internal combustion engine according to the present invention.

FIG. 6 is a flowchart showing the operation flow of another embodiment of the present invention.

[Explanation of symbols]

1 Internal combustion engine cylinder 2 Fuel injection valve 3 Fuel pump 4 Pressure regulator 5 Control means 6 Memory means 7 Operating state detection means 8 Fuel pressure sensor 9 Judgment means 10 Alarm means 11 Air flow sensor 12 Intake pipe 13 Distributor 14 Rotation sensor 15 Engine cooling water temperature sensor 16 Fuel tank 18 Electronic control circuit 19 Engine key switch 20 Alarm lamp 21 Battery

Claims (1)

[Claims] Claim 1: A fuel pump that injects and supplies fuel to an engine, a fuel pressure regulating valve that functions to keep the fuel pressure applied to the fuel injection valve constant with respect to atmospheric pressure or intake pressure, and a fuel that detects the fuel pressure. If the pressure sensor changes the fuel pressure after the fuel pump stops compared to the fuel pressure when the fuel pump is driven, or if the fuel pressure after the engine key switch is input and before the engine starts changes by more than a predetermined value, 1. A fuel leak self-diagnosis device for an electronically controlled fuel injection type internal combustion engine, comprising: determining means for determining that a fuel injection valve is leaking.