JP2876875B2 - Auxiliary air flow control valve failure diagnosis device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for diagnosing a failure of an auxiliary air flow control valve used for controlling idle rotation of an engine.

[0002]

2. Description of the Related Art In general, in an electronic engine centralized control system, an engine auxiliary air amount is controlled by feedback control so that an idle speed does not change due to a change with time of an engine or a load of an alternator or a power steering pump. , The idle speed is kept at a predetermined value.
An actuator for performing this feedback control is an auxiliary air amount control valve. If the auxiliary air amount control valve fails, various problems such as idle instability, high idle, and poor starting occur. Therefore, when a failure occurs,
Alternatively, it is necessary to diagnose the failure of this valve at the time of inspection.

As an apparatus for this purpose, for example, Japanese Patent Application No. Hei 2-1
No. 23575. In this device, the control duty value of the auxiliary air amount control valve is increased from 0% to 100%.
%, And if the amount of change in the engine speed at that time exceeds a predetermined reference value, it is determined that the engine is normal, and if not, it is determined that the engine has failed.

[0004]

However, if the engine has a problem such as a misfire, EGR (exhaust gas recirculation) has been continuously applied, or if the load has increased due to aging, the amount of auxiliary air Even if the control valve supplies the amount of auxiliary air according to the control signal, the amount of change in the engine speed at that time may be significantly lower than a predetermined reference value. For this reason, it has been difficult for the conventional diagnostic device to accurately determine the failure of the auxiliary air amount control valve. Therefore, the present invention has been made in view of such problems,
It is an object of the present invention to provide a failure diagnosis device capable of accurately determining a failure of an auxiliary air amount control valve even when a phenomenon affecting a change amount of an engine speed occurs.

[0005]

SUMMARY OF THE INVENTION For this reason, the present invention has been described with reference to FIG.
, An auxiliary air amount control signal output means 1 for outputting a control signal for controlling an auxiliary air amount control valve of the engine, an engine speed detecting means 2 for detecting an engine speed, Intake air amount detecting means 3 for detecting an intake air amount, a first engine speed when the control signal is a first control value, and a second engine speed when a second control value is used as the control signal. And a first comparing means 4 for comparing the difference between the first intake air amount and the second control value when the control signal is a first control value. and second comparison means 5 for comparing a second reference value the difference given between the second intake air amount, the first engine
The difference between the engine speed and the second engine speed is equal to the first reference value.
And the first intake air amount and the second intake air
When the difference from the amount is smaller than the second reference value, the auxiliary air amount
A determination means 6 for determining that the control valve has failed is provided.

[0006]

The auxiliary air amount control signal output means 1 outputs the first and second control values, the corresponding change in engine speed is compared with a first reference value, and the change in intake air amount 2 is compared with the reference value. Both change situation first the determination unit
When both are smaller than the first reference value and the second reference value
It is determined that the auxiliary air amount control valve is malfunctioning .
The operating state of the auxiliary air amount control valve is correctly grasped even if the engine speed is affected by other problems.

[0007]

FIG. 2 shows a hardware configuration of an embodiment of the present invention. In the engine control system 10, information signals are input to the engine control unit 11 from a group of sensors 15 such as an air flow meter, a water temperature sensor, an idle switch, and a crank angle sensor. A control signal is output to a group of actuators 16 such as an air amount control valve and an injector. The air flow meter constitutes the intake air amount detecting means of the present invention, and the engine speed can be obtained from the output of the crank angle sensor.

The diagnostic device 12 has an I / O interface, R
An OM, a RAM, and a CPU are provided to perform control, calculation, and determination of the device of the present embodiment. The determination unit 6, the first comparison unit 4, the second comparison unit 5, and the auxiliary air amount control signal of the present invention It functions as output means 1. The diagnostic device 12 uses the display means 14 to instruct the operator to perform an operation and to display the determination result. The operator operates the diagnostic device 12 and performs an input operation instructed by the display unit 14 through the input unit 13. As the input unit 13, a keyboard, a touch screen, or the like is used, and the input unit 13 can also be used as the display unit 14.

The diagnostic device 12 and the engine control unit 11 are connected by a communication line 17. Sensor group 15
The sensor values supplied to the engine control unit 11 and the control output values supplied to each of the actuator groups by the engine control unit 11 are transmitted to the diagnostic device 12 via the communication line 17.
Is also supplied. An operation command to the actuator group 16 and a pseudo sensor value are supplied from the diagnostic device 12 to the engine control unit 11. When these commands and the like are supplied from the diagnostic device 12, the engine control unit 11 preferentially follows them.

The diagnosis in the diagnostic device 12 is performed based on the following knowledge. That is, in FIG. 3, since the auxiliary air amount control valve is changed from fully closed to fully opened, the engine speed and the engine speed when the control duty value of the valve is changed from 0% to 100% as shown in FIG. FIG. 4 shows the amount of intake air, and FIG. 3 and 4, x indicates that the auxiliary air amount control valve is normal, y indicates that the auxiliary air amount control valve is normal but there is a problem that the EGR is continuously applied, and z indicates the auxiliary air amount control valve itself. Shows a case where is abnormal. In addition, a defect in which EGR is continuously applied is abbreviated as “EGR defect”.

When there is an EGR failure (y), the combustion state deteriorates. For this reason, even if the auxiliary air amount control valve is operating normally, as shown in FIGS. 3B and 4A, the change amount of the engine speed becomes considerably small.
The amount of change at this time is as small as when the auxiliary air amount control valve is abnormal. This is the reason why the conventional diagnosis device cannot execute the failure judgment accurately. On the other hand, when the auxiliary air amount control valve is operating normally (x), the auxiliary air is supplied according to the control duty value. Therefore EG
Even if there is an R defect, the amount of change in the intake air shows a value almost close to the normal amount of change as shown in FIGS. 3 (c) and 4 (b).

As described above, first, when the amount of change in the engine speed is equal to or more than a predetermined reference value, for example, N1, it is determined that the auxiliary air amount control valve is normal. This N1 corresponds to the first reference value of the present invention. Next, when the engine speed change amount is smaller than the reference value, the intake air change amount is compared with a predetermined reference value, for example, Q1. If the intake air change amount is smaller than Q1, it is determined that the auxiliary air amount control valve has failed. If the intake air amount is equal to or more than Q1, the auxiliary air amount control valve is determined to be normal. This Q1 corresponds to a second reference value of the present invention.

FIGS. 5 to 7 show flowcharts of the failure judgment in this embodiment. This processing is executed by the diagnostic device 12. When the program is started by operating the keyboard or the like of the input means 13, first, it is confirmed whether or not a precondition for executing the main failure determination is satisfied. Here, it is assumed that the neutral switch and the idle switch are both turned on (in that state), and that the engine water temperature is equal to or higher than a certain temperature (temperature at which warm-up is completed).

That is, first, in step 100,
The idle switch signal, the neutral switch signal, and the water temperature value are received as one frame data from the engine control unit 11. Next, at step 200, whether the neutral switch is on, at step 300, whether the idle switch is on, at step 400
It is checked whether the water temperature is 80 ° C. or higher. If the switches and the water temperature do not satisfy the above conditions, the messages shown in steps 210, 310 and 410 are output and displayed on the display means 14. The operator responds to this and takes necessary measures, and proceeds to step 500 when the conditions are satisfied.

Here, the engine control unit 11 is instructed to output the auxiliary air amount control signal as a first control value of "duty value 0%" (fully close the auxiliary air amount control valve). At step 510, the engine control unit 11 sends the engine speed N and the intake air amount Q
Is received for 10 seconds in a frame, and the data is R
Recorded in AM. Next, the routine proceeds to step 520, where the average value of the stored data for the last 5 seconds is calculated. The average value of the engine speed N is NL, and the average value of the intake air amount Q is QL. Immediately after changing the opening of the auxiliary air amount control valve, the state of the engine tends to be unstable. Therefore, the data for the last 5 seconds is used here. NL is the first engine speed of the present invention, and QL is the first intake air amount of the present invention.

In step 600, this time, the output of the auxiliary air amount control signal is set as the second control value and "duty value 100
% "(The auxiliary air amount control valve is fully opened). Step 61
At 0, data of the engine speed N, the intake air amount Q, and the intake manifold negative pressure P are received from the engine control unit 11 for 10 seconds, and the data is recorded in the RAM. Proceeding to step 620, the average value for the last 5 seconds of the data stored in step 610 is calculated. The average value of the engine speed N is NH, the average value of the intake air amount Q is QH, and the average value of the intake manifold negative pressure P is PH. NH is the second engine speed of the present invention, and QH is the second intake air amount of the present invention.

In step 630, a reference value Q1 of the amount of change in intake air corresponding to the average value PH of the intake manifold negative pressure at that time is read. The reference value Q1 of the intake air change amount is determined based on the amount of air supplied to the engine via the auxiliary air amount control valve when the auxiliary air amount control valve is fully opened. This value increases when the negative pressure of the engine at that time is high, and decreases when the negative pressure is low. Therefore, in this embodiment, the reference value Q1 is set as a table constant of the intake manifold negative pressure P of the engine, and the reference value Q1 of the intake air change amount is determined with reference to this.

Next, at step 700, the engine speed change amount (NH-NL) is calculated from the engine speeds NL and NH when the auxiliary air amount control valve is fully closed and fully open calculated at steps 520 and 620. You. This is compared with a predetermined reference value N1. If the engine speed change amount is equal to or larger than the reference value N1, step 710 is executed.
The message "Auxiliary air amount control valve is normal" is output and displayed on the display means 14. When the engine speed change amount is smaller than the reference value N1, the routine proceeds to step 800. Here, the intake air amount Q at the time of fully closing and fully opening the auxiliary air amount control valve calculated at steps 520 and 620
From L and QH, the amount of change in intake air (QH-QL) is calculated. This is compared with a predetermined reference value Q1.

When the change amount of the intake air is equal to or more than the reference value Q1, the auxiliary air amount control valve is normal from the above description, but there are other problems (for example, misfiring, EGR stoppage, etc.). Accordingly, the process proceeds to step 820, and a message of "auxiliary air amount control valve is normal (other problem exists)" is output and displayed on the display means 14.
When the change amount of the intake air is smaller than the reference value Q1, the auxiliary air amount control valve itself has an abnormality, as described above. Therefore, the process proceeds to step 810, and the message “Auxiliary air amount control valve abnormality” is displayed on the display unit 14.
Is output to

In the above embodiment, the first control value is a value for fully closing the auxiliary air amount control valve, and the second control value is a value for fully opening the auxiliary air amount control valve. Without being limited to the above, it is possible to appropriately set a control value by which a significant comparison can be obtained with respect to the change amounts of the engine speed and the intake air amount.

FIG. 8 shows the configuration of the second embodiment. The diagnostic device 1 is connected to a group of sensors 15 and a group of actuators 16 instead of being connected to the engine control unit 11.
2 '. The diagnostic device 12 ′ directly reads the sensor values including the engine speed and the intake air amount, and overrides the engine control unit 11 to output a control signal to the auxiliary air amount control valve in the actuator group. In this manner, similarly to the above description, the amount of change in the engine speed and the amount of intake air can be obtained, and the failure of the auxiliary air amount control valve can be accurately determined based on the result of comparison with the reference value.

[0022]

As described above, according to the present invention, the two parameters of the change in the intake air and the change in the engine speed when the control output value of the auxiliary air quantity control valve is changed are determined as the failure determination parameters.
Are used together, and both change statuses are
If it is determined that the auxiliary air amount control valve is malfunctioning when it is smaller, there is a problem such as a misfire in the engine or the EGR is continuously applied, or an increase in the load of the engine itself due to aging. However, the operating state of the auxiliary air amount control valve can be accurately determined. Also, there is an advantage that the existence of these other defects can be determined at the same time. Therefore, it is possible to improve the accuracy of failure diagnosis, shorten the diagnosis time, reduce labor costs, and prevent unnecessary parts replacement.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a block diagram showing an embodiment of the present invention.

FIG. 3 is a diagram showing an intake air amount and an engine speed when a control signal is changed.

FIG. 4 is a diagram showing changes in intake air amount and engine speed.

FIG. 5 is a flowchart illustrating a processing procedure in the embodiment.

FIG. 6 is a flowchart illustrating a processing procedure in the embodiment.

FIG. 7 is a flowchart illustrating a processing procedure in the embodiment.

FIG. 8 is a block diagram showing another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Auxiliary air amount control signal output means 2 Engine speed detection means 3 Intake air amount detection means 4 First comparison means 5 Second comparison means 6 Judgment means 10 Engine control system 11 Engine control unit 12, 12 'Diagnostic device 13 Input means 14 Output means 15 Sensor group 16 Actuator group 17 Communication line NL First engine speed NH Second engine speed N1 First reference value QL First intake air amount QH Second intake air amount Q1 First Reference value of 2

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-61-45950 (JP, A) JP-A-3-229945 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F02D 41/22 F02D 41/16 F02D 9/02 341 F02D 45/00 364

Claims (1)

(57) [Claims] 1. An auxiliary air amount control signal output unit for outputting a control signal for controlling an auxiliary air amount control valve of an engine, an engine speed detecting unit for detecting an engine speed, and an intake air amount of the engine. And a difference between a first engine speed when the control signal is the first control value and a second engine speed when the control signal is the second control value. First comparison means for comparing the first control value with the first reference value, and first intake air amount when the control signal is a first control value and second intake air when the control signal is a second control value Second comparing means for comparing the difference between the first engine speed and the second engine speed with a second reference value .
The difference from the engine speed is smaller than the first reference value, and
The difference between the first intake air amount and the second intake air amount is the second
When the auxiliary air flow control valve is
An auxiliary air amount control valve failure diagnosis device, comprising: a determination unit that determines that a failure has occurred.