JPH06213050A - Trouble diagnoser of fuel system for internal combustion engine - Google Patents

Abstract

PURPOSE:To make a trouble judgment on a fuel system achievable without doing a road test and the discahrge test of a fuel pump single by comparing a lowering quantity of fuel pressure to be detected with a judgment reference value calculated on the basis of a driving state at that time and a fuel injection quantity. CONSTITUTION:Trouble in a fuel system C provided with a fuel injection quantity setting means B setting the injection quantity of a fuel injection valve on the basis of an output signal of a driving state detecting means A is diagnosed. This trouble diagnoser is provided with an actual fuel pressure variation detecting means I detecting a variation in actual fuel pressure in the fuel system C in particular and a reference fuel pressure variation operational means J seeking a variation reference value of fuel pressure in this system C in use of both these means A and B. In addition, on the basis of a comparison between a detected value of the mean I and a variation reference value of the means J, trouble in the system C is judged by a trouble judging means K. In brief, a fuel pressure lowering quantity reference value conformed to a racing state is calculated, and in the case where a lowering quantity in the actual fuel pressure has exceeded the fuel pressure lowering quantity reference value, a trouble diagnosis is displayed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a failure diagnosis system for a fuel supply system of an internal combustion engine, and more particularly to a failure diagnosis of the fuel supply system for an internal combustion engine without spending a great deal of man-hours and time such as load test and single item inspection. The present invention relates to a diagnostic device that can be discriminated.

[0002]

2. Description of the Related Art A fuel supply device is provided in an internal combustion engine mounted on a vehicle such as an automobile. The fuel pump system is the most common cause of failure of the fuel supply device. Factors are broadly divided into “no fuel supply” (for example, due to operation stop of fuel pump due to defective wiring of fuel pump, operation stop due to lock of fuel pump main body) and “insufficient flow rate” (for example, , Due to insufficient discharge of the fuel pump body).

Therefore, conventionally, one of the methods for diagnosing the failure of the fuel supply device is, for example, the pressure of the fuel discharged from the fuel pump (hereinafter referred to as fuel pressure) at a predetermined fuel pressure during a steady state such as idling. There is a method for determining whether or not the fuel supply device is normal by comparing with a reference value (see Nissan Fairlady Z Maintenance Manual, July 1989, page B-159).

[0004]

However, in the above-mentioned failure diagnosis method, since the failure judgment is made only by the absolute value of the fuel pressure in the steady state, the above-mentioned "no fuel is supplied" or extreme "insufficient flow rate" is caused. Can be determined, but there is a problem that it is difficult to determine “insufficient flow rate” that occurs in a region where a large amount of fuel flow rate is required, such as at high rotation speed, high load, and acceleration. And when this "insufficient flow rate" occurs,
There has been a problem that problems such as insufficient output of the internal combustion engine, poor acceleration, hesitation, etc. appear.

Therefore, when a vehicle having such a fuel supply device trouble phenomenon enters a maintenance factory, a maintenance worker connects the fuel pressure gauge to the fuel pipe of the fuel supply device in order to narrow down the defective portion. Do a load test
Alternatively, it is necessary to test the discharge amount of the fuel pump alone, and it is necessary to spend a great deal of man-hours and time for determining the failure of the fuel supply device.

The present invention has been made to solve the above-mentioned conventional problems, and it is possible to determine the failure of the fuel supply device without performing a load test or a discharge amount test of the fuel pump alone. Has an aim.

[0007]

FIG. 1 shows the configuration of a failure diagnosis apparatus for a fuel supply system for an internal combustion engine according to the present invention which achieves the above object. The present invention diagnoses a failure of a fuel supply device C provided with a fuel injection amount determination means B that determines the injection amount of a fuel injection valve based on an output signal of an operation state detection means A that detects the operation state of an internal combustion engine. An operating state control means F for controlling the internal combustion engine to a predetermined operating state, and a fuel pressure control means G for instructing the fuel supply device C to keep the fuel pressure supplied to the fuel injection valve constant. A work instruction means H for outputting an instruction to change the operating state of the internal combustion engine from the predetermined operating state to another operating state, and an actual operation in the fuel supply device C when the operating state of the internal combustion engine changes to another operating state Of the actual fuel pressure change detecting means I for detecting a change in the fuel pressure of the internal combustion engine and the output signal of the operating state detecting means A and the fuel injection amount determining means B are used to change the fuel when the operating state of the internal combustion engine changes to another operating state. Supply device Of the fuel supply change C based on the comparison between the detected value of the actual fuel pressure change detection means I and the reference change value of the reference fuel pressure change calculation means J and the reference fuel pressure change calculation means J for obtaining the change reference value of the fuel pressure. The gist is to have a failure determination means K for determination.

[0008]

According to the failure diagnosis apparatus for the fuel supply system for an internal combustion engine of the present invention, after the idling state of the internal combustion engine is detected, an instruction is given to make the fuel pressure of the fuel supply system constant, and in this state no load is applied. A blanking instruction is given. When a predetermined idling of the internal combustion engine is executed, the actual amount of decrease in fuel pressure is detected, and a reference value for the amount of decrease in fuel pressure is calculated according to the state of idling, and the actual amount of decrease in fuel pressure is reduced in fuel pressure. When the quantity reference value is exceeded, a failure diagnosis of the fuel supply device is displayed.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 2 is a diagram showing a part of a fuel supply system for an internal combustion engine (engine) and a basic construction of an embodiment of a failure diagnosis system 10 of the present invention.

First, a brief description will be given of a fuel supply system for an engine. Reference numeral 1 denotes an engine control unit (hereinafter referred to as ECM), which is used for various control of an engine (not shown). Information is input from various sensors 2 such as sensors and idle SWs, and various actuators 3 such as indicators and power transistors are controlled based on the information. A fuel pipe 4 supplies fuel to the engine from a fuel pump (not shown), and a pressure regulator 5 is attached to the fuel pipe 4. The pressure in the fuel pipe 4 is changed by the pressure applied to a diaphragm chamber (not shown) in the pressure regulator 5.

The pressure regulator 5 is connected to the ECM 1, and a fuel control solenoid 6 is provided in the middle thereof. The fuel control solenoid 6 switches the pressure applied to the diaphragm chamber in the pressure regulator 5 to the atmospheric pressure or the pressure in the intake manifold according to the operating state of the engine at that time according to a command from the ECM 1.

Next, the failure diagnosis apparatus 10 of the present invention for diagnosing the failure of the fuel supply apparatus is the diagnostic device 1 in this embodiment.
1, a display device 12, an input device 13, and a fuel pressure sensor 14. The diagnostic device 11 is at least I / O,
It is configured to include a ROM, a RAM, and a CPU, and performs control, calculation, and determination of the failure diagnosis device 10 of the fuel supply device of this embodiment. Further, the display device 12 is for displaying work instructions and judgment results to a worker who performs a failure diagnosis by the diagnostic device 11, and the input device 13 is a keyboard or a touch screen for operating the diagnostic device 11. is there. Therefore, when a touch screen is used as the display device 12, the display device 12 can be used also as the input device 13. The fuel pressure sensor 14 is attached to the fuel pipe 4 of the fuel supply device, detects the pressure in the fuel pipe 4 and outputs it to the diagnostic device 11.

The fault diagnosis device 10 configured as described above.
The diagnostic device 11 is used by being connected to the ECM 1 by a communication line 15. The output value of the sensor 2 and the output value of the actuator 3 used by the ECM 1 for control are transmitted to the diagnostic device 11 via the communication line 15. Further, the ECM 1 preferentially follows the instruction from the diagnostic device 11.

Next, the procedure of the fault diagnosis performed by the diagnostic device 11 of the fault diagnostic device 10 of the embodiment configured as described above will be described with reference to the flowchart of FIG. It should be noted that the routine shown in this flowchart is executed by the diagnostic device 11
From ECM1.

First, at step 301, the engine speed calculated by the ECM 1 from the signals from the crank angle sensor and the idle SW and the state of the idle SW (O
N or OFF) is acquired from the ECM 1 for one frame data via the communication line and stored in the RAM as NRPM1 (engine speed) and IDLE1 (state of idle SW), respectively.

At the next step 302, the state IDLE1 of the idle SW stored at step 301 is turned on.
And the engine speed NRPM1 is 500
It is determined whether the speed is rpm or more. And Idol S
When the state of W is ON and the engine speed is 500 rpm or more, it is determined that the engine is in the idling state, and the process proceeds to step 303. Otherwise, the process returns to step 301. When the engine is in the idling state, the process proceeds to step 3
03, the fuel pressure of the fuel pipe 4 is constant (for example, 3.
A command to turn on the fuel pressure control solenoid 6 (in this case, the diaphragm in the pressure regulator 5 is exposed to the atmospheric pressure) is output to the ECM 1 via the communication line 8 in order to hold the fuel pressure control solenoid 6 at 0 kg / cm @ 2). And step 30
4, the engine speed NRPM, the idle SW state IDLE1, the throttle opening TVO, and the fuel injection pulse width Ti are acquired every 10 msec from the ECM 1 through the communication line 15, and the fuel pressure Fp is acquired every 10 msec. It is acquired from the sensor 14 and each starts to be stored in the RAM. In step 305 after this,
An instruction to run the engine once with no load is displayed on the display 12 to the operator.

In step 306, it is determined whether or not the idling of the engine displayed in step 305 has been executed. The determination as to the presence or absence of this idling is made in step 304.
It is possible to determine whether or not the data of the IDLE1 of the idle SW, which has started to be stored, has changed from the OFF state to the ON state even once. And the state I of the idle SW
If the data of DLE1 is changed from OFF to ON even once, it is determined that the operator has stepped on the accelerator according to the instruction in step 305, the process proceeds to step 307, the storage of the data is finished, and then the step is performed. The fuel pressure control solenoid 6 set in 303 is returned to the normal ECM1 control state. If the data in the idle SW state IDLE1 has not changed from the OFF state to the ON state even once, the process returns to step 304 and the data storage is continued.

In step 308, which follows the step 307, the change amount ΔTVO of the throttle opening TVO for 100 msec is first calculated from the data recorded in the above step, and the maximum value of the change amount ΔTVO is set to ΔTVOmax. Every (MAX (ΔTVO) in Figure 3 →
ΔTVOmax), and the difference between the maximum value Fpmax and the minimum value Fpmin of the fuel pressure Fp is calculated as ΔFp.

In the next step 309, it is judged whether or not the maximum value ΔTVOmax of the change amount is larger than the value TVO1 stored in advance in the ROM of the diagnostic device 11. ΔTV
If Omax is not larger than TVO1, it is determined that the idling speed is slow, the process returns to step 304, and step 3 is performed again.
The processing from 04 to step 308 is executed to store and empty the data, and if not, step 310
Proceed to. In step 310, the fuel injection pulse width Ti (t) and the engine speed NRP while the idle SW state IDLE1 of the stored data is in the OFF state
After multiplication by M (t), the multiplication result data Ti (t)
× NRPM (t) are all added to obtain A. Next, A is multiplied by a predetermined conversion coefficient K (a coefficient for converting Ti × NRPM into a fuel injection amount) to obtain a fuel injection amount KA.

Next, at step 311, a table of the fuel injection amount KA calculated at step 310, that is, the fuel injection amount KA and the fuel pressure decrease amount reference value Fpstd stored in the ROM in advance from the value of the total fuel injection amount ( (Not shown), the fuel pressure decrease amount reference value Fpstd at that time is determined. Then, in step 312, the difference ΔFp between the maximum value and the minimum value of the fuel pressure calculated in step 308 described above is
It is determined whether or not it is larger than the fuel pressure decrease amount reference value Fpstd calculated in step 311. ΔF in step 312
When p ≧ Fpstd, that is, when the actual fuel pressure decrease amount ΔFp as a result of idling exceeds the fuel pressure reduction reference value Fpstd calculated by idling, the fuel is supplied from the fuel supply device side. When it is determined that the flow rate of the fuel supply device having a small amount is "insufficient flow rate", the process proceeds to step 313, where "insufficient flow rate" is displayed to the operator via the display 5, and this routine is finished.
On the other hand, if ΔFp <Fpstd in step 312, it is determined that the fuel pressure is normal, the process proceeds to step 314, the operator indicates “normal state” via the display 5, and this routine ends.

Next, FIG. 4 shows a timing chart of the present embodiment. The engine idling display described in step 305 of FIG. 3 is performed, and the engine idling is actually performed at time t1. , Time change of each part of the engine when the idling of the engine is finished at time t2. In FIG. 4, (a) shows a change in engine speed (rpm), (b) shows a throttle opening detected by a throttle sensor (represented by voltage V), and (c) shows a fuel injection pulse width. (Ms), (d)
Shows the state of the idle SW, (e) shows the fuel pressure under normal conditions (kg / cm2), and (f) shows the fuel pressure under abnormal conditions (kg).
/ Cm2).

When the idling is executed at the time t1, as shown in FIG.
As shown in (a), the engine speed increases and then decreases. Further, as shown in FIG. 4 (b), the opening of the throttle valve increases only during idling, and as shown in FIG. 4 (c), the fuel injection pulse width increases and fuel is injected. As shown in 4 (d), the idle SW is turned off. In this idling state, when the fuel supply device is normal, the throttle valve is opened, and even if fuel injection is performed, the pressure regulator operates if the discharge amount of the fuel pump is sufficient. Therefore, in this case, FIG.
As shown in, even if the engine is idled and the fuel injection amount is suddenly increased, the fuel pressure is hardly reduced. On the other hand, if there is an abnormality in the fuel supply device and, for example, the discharge amount of the fuel pump is insufficient and the flow rate is insufficient, as shown in FIG. If the injection amount is suddenly increased, the fuel pressure will decrease.

Therefore, as described in step 312 of FIG. 3, when the fuel pressure decrease amount Fp exceeds the fuel pressure decrease amount reference value Fpstd, it can be determined that the fuel supply device is "insufficient in flow rate". It can be displayed that the supply device is abnormal.

[0025]

As described above in detail, according to the failure diagnosis apparatus for the fuel supply system for the internal combustion engine of the present invention, when the operating state of the engine is changed while the fuel pressure is kept at a predetermined value. Since the detected fuel pressure decrease amount is compared with the operating condition at that time and the judgment reference value calculated based on the fuel injection amount to determine the failure, the maintenance worker of the fuel supply device has a problem of drivability. Insufficient flow rate of the fuel supply device, which is one of the causes of the above problem, can be accurately determined in a short time without performing a load test or a discharge amount test of a single fuel pump.

Therefore, there is an effect that the failure diagnosis work of the fuel supply device can be significantly improved by shortening the failure diagnosis time.

[Brief description of drawings]

FIG. 1 is a block diagram showing the principle configuration of a failure diagnosis device for a fuel supply device for an internal combustion engine according to the present invention.

FIG. 2 is a configuration diagram showing a configuration of an embodiment of a failure diagnosis device for a fuel supply system of the present invention together with a part of a fuel supply system for an internal combustion engine.

FIG. 3 is a flowchart showing an example of a failure diagnosis procedure by a diagnostic device in the failure diagnosis apparatus for a fuel supply apparatus of the present invention.

4 (a) to (f) are timing charts for supplementarily explaining the flow of the failure diagnosis procedure of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ECM 2 sensor 3 actuator 4 fuel piping 5 pressure regulator 6 fuel control solenoid 10 failure diagnosis device for fuel supply device of the present invention 11 diagnostic device 12 display means 13 input means 14 fuel sensor 15 communication line

Claims (1)

[Claims] 1. An apparatus for diagnosing a failure of a fuel supply device, comprising fuel injection amount determining means for determining an injection amount of a fuel injection valve based on an output signal of an operating state detecting means for detecting an operating state of an internal combustion engine. An operating state control means for controlling the internal combustion engine to a predetermined operating state; a fuel pressure control means for instructing the fuel supply device to keep the fuel pressure supplied to the fuel injection valve constant; A work instruction means for outputting an instruction to change the operating state of the engine from the predetermined operating state to another operating state, and an actual fuel pressure of the fuel supply device when the operating state of the internal combustion engine changes to another operating state. An actual fuel pressure change detecting means for detecting a change, and the fuel when the operating state of the internal combustion engine changes to another operating state using the output signals of the operating state detecting means and the fuel injection amount determining means. A reference fuel pressure change calculation means for obtaining a change reference value of fuel pressure in the fuel supply device, and a failure of the fuel supply device based on a comparison between a detected value of the actual fuel pressure change detection means and a change reference value of the reference fuel pressure change calculation means. A failure diagnosis device for an internal combustion engine fuel supply device, comprising: