JPH0486350A - Air intake device of internal combustion engine - Google Patents

Abstract

PURPOSE:To cope with malfunction before it takes place on account of abnormality by detecting, by means of testing control, any abnormality of the control system of a second throttle valve driven and controlled by a motor either than a motor used for a first throttle valve which interlocks to an acceleration pedal. CONSTITUTION:A test control means E which makes testing control so as to place a second throttle valve B in a set opening under such a condition that a first throttle valve opening detected by a first throttle valve opening detection means D is at a specified value or less under a condition other than the specified one, in an air intake device provided in its intake system, with a first throttle valve A interlocked to the acceleration operation and opening-controlled, and the second throttle valve B subjected to throttle control under the specified condition detected by a control condition detection means C and maintained in its fully opened state normally. In the case when the opening of the second throttle valve B detected by a second throttle valve opening detection means E in the test operation is not converged to the set value within a specified time, the second throttle valve B is diagnozed by a diagnosis means G to involve some abnormality in its control system.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention includes a first throttle valve in the intake system whose opening is controlled in conjunction with accelerator operation, and a throttle valve which is throttle-controlled under predetermined conditions and is always kept fully open. The present invention relates to an intake system for an internal combustion engine including a second throttle valve, and particularly relates to a device for diagnosing an abnormality in a control system of the second throttle valve.

<Conventional technology> The intake system of an internal combustion engine has a conventional first valve that is linked to accelerator operation.
A second throttle valve is provided in series with the throttle valve, and when slip occurs in the driving wheels when driving on a snowy road, etc., the second throttle valve is throttle-controlled by a throttle actuator driven by a motor to reduce engine output. There is a traction control device (hereinafter referred to as a traction control device) that suppresses slip by controlling the traction control device (see Japanese Patent Laid-Open No. 192824/1982).

Furthermore, some such traction control devices diagnose abnormalities such as motor disconnection or drive circuit damage by checking whether the second throttle valve converges to the target opening within a predetermined time during traction control.

<Problem to be solved by the invention> However, in the conventional diagnosis method described above, diagnosis cannot be performed unless the second throttle valve is actually throttled to the target opening under a predetermined condition (in traction control, when a wheel slip occurs). First, since the method detects an abnormality only after it occurs, there is a problem in that it is not possible to deal with the abnormality.

The present invention has been made in view of these conventional problems, and provides an intake system for an internal combustion engine that solves the above problems by making it possible to detect the occurrence of abnormality before the abnormal control is executed. The purpose is to

<Means for Solving the Problems> For this reason, the present invention, as shown in FIG. In an intake system for an internal combustion engine, the second throttle valve is throttle-controlled under a detected predetermined condition and is normally kept fully open. a control means for test-controlling a second throttle valve to a set opening on the condition that the opening of the first throttle valve is below a predetermined value; diagnostic means for diagnosing that there is an abnormality in the control system of the second throttle valve when the opening degree of the second throttle valve detected by the throttle valve opening degree detection means does not converge to the set opening degree within a predetermined time; It is composed of .

<Operation> When the first throttle valve opening detection means detects that the opening of the first throttle valve is below a predetermined value when the condition is not the predetermined condition detected by the control condition detection means,
Des 1~ The control means performs throttle control to bring the second throttle valve to the set opening degree.

If the second throttle valve does not reach the set opening within a predetermined period of time as a result of the test control, the diagnostic means diagnoses that there is an abnormality in the control system of the second throttle valve.

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

In FIG. 2 showing a system configuration of an embodiment applied to a traction control device, an intake passage 1 of an engine includes first throttle valves 4 which are operated in conjunction with an accelerator pedal 2 via an accelerator wire 3; A throttle valve 5, which is not interlocked with the accelerator operation, is installed in series on the upstream side of the throttle valve 5.

The opening degree of the second throttle valve 5 is controlled by a motor 7 connected via a rod 6 and serving as a throttle actuator. The second throttle valve 5 is normally kept fully open by the biasing force of the return spring 8, and when current is supplied to the motor 7 in response to a control signal from the motor control unit 9, the motor 7 rotates by a predetermined angle. In conjunction with this, the second throttle valve 5 is closed.

Further, the opening degree TV of the first throttle valve 4 is determined by the first throttle sensor lO as the first throttle valve opening detection means.
At the same time, the opening degree TV○2 of the second throttle valve 5 is detected by the second throttle sensor 11, and these opening degree TV○2 signals are sent to the sensor input of the motor control unit 9. The signal is input to a circuit 91, A/D converted by an A/D converter 92, and then input to a throttle control circuit 93 comprised of a CPU.

On the other hand, a traction control unit (not shown) detects the slip state of the drive wheels based on signals from wheel speed sensors that detect the rotational speeds of the front, rear, left, and right wheels of the vehicle, and when a slip rate exceeding a predetermined value occurs, l-traction control is performed. In order to perform this, a target opening degree of the second throttle valve 5 is set, and the target opening degree signal is output to the throttle control circuit 93 of the motor control unit 9.

Then, the throttle control circuit 93 outputs a feedback control signal to the drive circuit 94 to control the second throttle valve 5 based on the deviation between the target opening degree and the detected opening degree, and the drive circuit 94 drives the motor 7. Throttle control is performed to converge the second throttle valve 5 to the target opening.

On the other hand, if the opening degree of the first throttle valve 4 is below a predetermined value at times other than when such traction control is requested, the drive circuit sends a feedback control signal to converge the second throttle valve 5 to the set opening degree at regular time intervals. 94, and if the opening does not converge to the set opening within a predetermined time, it is diagnosed that there is an abnormality in the control system of the second throttle valve 5.

Next, a routine for diagnosing an abnormality in the traction control and the second throttle valve control system according to the present invention will be explained with reference to FIG.

In step 1 (denoted as S in the figure), the target opening degree TVOR of the second throttle valve 5 from the traction control unit is input.

Step 2 is the opening degree TVO of the first throttle valve 4 detected by the first throttle sensor 1o.

and the second detected by the second throttle sensor 11.
The opening degree TVO of the throttle valve 5 is A/D converted and read.

Step 3 is the target opening TVO input in step 1.
It is determined whether R is fully open.

Then, when the target opening degree TVOR is other than fully open, the process proceeds to step 4 in order to execute the above-mentioned traction control.

In step 4, the timer TMINTV for measuring the execution cycle of the diagnosis described later, the timer TMT2OK for measuring the normal time for determining that the diagnosis is normal, and the flag FTV2CHK indicating that the diagnosis is in progress are reset. do.

In step 5, the target opening TVO of the second throttle valve 5
An output value MOTOUT of the motor 7 to be given in feedback control is calculated based on R and the detected opening TVO3.

In step 6, the output value MOT calculated in step 5 is
A drive signal corresponding to OUT is output to the drive circuit 93.

In step 7, the target opening TVOR and the detected opening TV O2
It is determined whether the absolute value of the deviation from the value has converged to a value smaller than a predetermined value β.

When it is determined that the process has converged, the process proceeds to step 8, where the timer TMT2ERR, which measures the duration of the abnormal state, is reset to 1, and this routine ends.

If it is determined in step 7 that the convergence has not been achieved, the process proceeds to step 9, where the timer TMT 2ERR is incremented.

Next, the process proceeds to step 10, and the timer TMT 2ER
The value of R, that is, the duration of the abnormal state or the predetermined time TTV2N
It is determined whether or not the value has exceeded G.

If the above occurs, the process proceeds to step 11, where it is diagnosed that there is an abnormality in the control system of the second throttle valve 5, and the process proceeds to step 12, where a fail-safe program (for example, a traction control command Even if there is
・Do not execute traction control, etc.).

On the other hand, in step 3, the target opening degree TV of the second throttle valve 5
If it is determined that the OR is fully open, the process proceeds to step 13 where it is determined whether the detected opening TVO2 is fully open or not, and if it is not fully open, the traction control has been canceled during execution and is on the way back to fully open. I judge this and proceed to step 4, but
If it is determined that the engine is fully open, the process proceeds to step 14 to execute test control according to the present invention. That is, the l/traction control unit (not shown), the wheel speed sensor, and the functions of steps 1 to 3 and step 13 correspond to the control condition detection means.

In step 14, the timer TMINV is incremented.

In step 15, it is determined whether the value of the timer TMINV has reached a predetermined value TMCHEK.

If the flag has not been reached, proceed to step 16 and set the flag F.
Determine whether or not TV2CHK is set. If it is reset, proceed to step 17 and set motor 7.
After setting the output value MOTOUT to 0, the process proceeds to step 6. In this case, the output to the motor 7 is stopped and the second throttle valve 5 is kept fully open.

Furthermore, when it is determined in step 15 that the value of timer TMINTV has reached the predetermined value TMCHEK, the process proceeds to step 18, where timer TMINTV is reset and flag F
After setting the TV2CHK, the process proceeds to step 19.

Also, if it is determined in step 16 that the flag F TV 2 CHK is set, the process proceeds to step I9.

In step 19, the opening degree T■01 of the first throttle valve 4 is
It is determined whether or not the opening degree is smaller than a predetermined value TVICHK. Here, the predetermined value TVICHK is set to a value that does not have any effect even if the throttle control is performed when the second throttle valve 5 is controlled to the set opening degree on a test basis, as will be described later.

It's decided.

In step 20, the target opening degree TV of the second throttle valve 5
Set OR to the set opening TV2CHK for test control. As described above, this set opening degree TV2CHK is set to a value close to the predetermined value TVICHK or a value higher than the predetermined value TVICHK in order to eliminate the influence.

In step 21, the target opening TVOR and the detected opening TV
It is determined whether the absolute value of the deviation from O2 has converged to a value smaller than a predetermined value α.

If the process has not converged, the process proceeds to step 22 to reset the timer TMT20K, and then proceeds to step 5 and subsequent steps. After that, in step 7.10, the absolute value of the deviation between the set opening TV2CHK and the detected opening T■02 converges to be smaller than the predetermined value β within a predetermined time TTV2NG in the same manner as the abnormality diagnosis during traction control. If not, it is diagnosed that the control system of the second throttle valve 5 is abnormal.

That is, the functions of step 20 and steps 5 and 6 correspond to test control means, and the functions of step 7 to step 1 correspond to diagnostic means.

If it is determined in step 21 that the absolute value of the deviation between the target opening TVOR set in the set opening TV2CHK and the detected opening TVO2 has converged to be smaller than the predetermined value α, the process proceeds to step 23. Increment the timer TMT20K that measures the duration of this state, and step 24
Then, it is determined whether the value has reached the predetermined value TTV2OK.

When it is determined in step 24 that TTV20K has been reached, it is determined that the control system for the second throttle valve 5 is stable in a normal state, that is, the control system of the second throttle valve 5 is normal, and the process proceeds to step 25 to set the flag FTVCHK. Reset.

As a result, the timer TMINTVO value is set to TMCH
Test control is stopped until EK is reached.

In addition, when it is determined in step 24 that TTV2OK has not been reached, the set opening TV2 is temporarily set during the control.
Since it may be approaching CHK, the process advances to step 5 to continue abnormality diagnosis through test control.

In other words, until an abnormality is detected, abnormality diagnosis is periodically performed at a predetermined cycle.

In this way, an abnormality in the control system of the second throttle valve 5 can be detected before entering the traction control, so that it is possible to prevent malfunctions from occurring due to the abnormality.

<Effects of the Invention> As explained above, according to the present invention, an abnormality in the control system of the second throttle valve can be detected by performing test control that does not affect others before performing the original control. ,
This allows countermeasures to be taken before malfunctions due to abnormalities occur.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, and FIG. 2 is a block diagram showing the configuration of the present invention.
FIG. 3 is a flowchart showing a control routine for the second throttle valve including abnormality diagnosis in the embodiment of the present invention. 1... Intake passage 4... First throttle valve 5
...Second throttle valve 7...Motor 9...
・Motor control unit IO...First throttle sensor 11...Second throttle sensor Patent applicant: Nissan Motor Co., Ltd. Agent Patent attorney Fujio Sasashima

Claims (1)

[Claims] The intake system of the engine includes a first throttle valve whose opening is controlled in conjunction with accelerator operation, and a second throttle valve which is throttle-controlled under a predetermined condition detected by a control condition detection means and is normally kept fully open. In the intake system for an internal combustion engine, when the opening of the first throttle valve, which is detected by the first throttle valve opening detection means at a time other than the predetermined condition, is equal to or less than a predetermined value, the second throttle is A test control means for test controlling the valve to a set opening degree, and an opening degree of the second throttle valve detected by the second throttle valve opening degree detection means during the test operation converges to the set opening degree within a predetermined time. An intake system for an internal combustion engine, comprising: a diagnostic means for diagnosing that there is an abnormality in the control system of the second throttle valve when the second throttle valve does not operate properly.