JPH06229301A - Output control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent engine output from being increased unexpectedly by controlling objective-throttle opening and cutting fuel appropriately when any abnormal condition takes place in the throttle valve control system of an internal combustion engine whose throttle valve is controlled by a step motor. CONSTITUTION:Angle sensors 3,4 which detect an oscillation angle of an accelerator pedal and a opening sensor 5 which detects the opening degree of a throttle valve 1 driven by a step motor 2 are provided. Each of sensor signals AP1s, AP2s and THs are given to a FI-CPU10 which determines a fuel injection valve control signal INJ and an ignition magnetic control signal IG and to a DBW- CPU11 which determines an exciter phase phi and a duty D of a current supplied to a step motor 2. A target-throttle opening is limited when one of respective sensors 3, 4, 5 and the step motor 2 is out of order in this CPU11, and also control process is carried out to effect fuel cut when the number of revolution of engine exceeds its specific level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an output control device for an internal combustion engine, and more particularly to a fail safe technique in throttle valve control.

[0002]

2. Description of the Related Art Recently, an accelerator pedal that detects the amount of depression of the accelerator pedal has replaced the conventional mechanical throttle valve drive system that transmits the operation amount of the depression of the accelerator pedal to an intake throttle valve (throttle valve) via a throttle wire. A drive system that includes an angle sensor and controls a motor that drives a throttle valve according to the output of the sensor is known.

The drive system has a throttle valve opening sensor for detecting the opening of the throttle valve, and drive control is performed by feeding back the output of the sensor.

Therefore, if the throttle valve angle sensor is not normal or the accelerator pedal angle sensor or the motor itself is abnormal, accurate drive control of the throttle valve cannot be performed. Therefore, conventionally, when the above abnormality is detected, measures such as stopping the control of the motor, disconnecting the connection between the throttle valve and the motor by turning off the electromagnetic clutch, or unconditionally interrupting the ignition have been taken. (Patent No. 4,393,833).

[0005]

[Problems to be Solved] Therefore, the driver has no choice but to stop the driving, and the traveling becomes difficult thereafter, so that the vehicle cannot be moved urgently or traveling home. Further, the harmful exhaust components are discharged by shutting off the ignition, which is not preferable in terms of exhaust characteristics.

The present invention has been made in view of the above points, and an object thereof is to provide an output control device for an internal combustion engine capable of maintaining a certain degree of travel even if an abnormality occurs in the throttle valve control system. It is in.

[0007]

In order to achieve the above object, the present invention provides a throttle valve provided in an intake passage of an internal combustion engine, an accelerator pedal angle sensor for detecting a depression angle of an accelerator pedal, and Target throttle valve angle setting means for determining a target throttle valve opening according to the output of the accelerator pedal angle sensor, a drive circuit for driving the throttle valve based on the target throttle valve opening, and a supply by the drive circuit A step motor that controls the opening and closing of the throttle valve by controlling the electric current, a throttle valve opening sensor that detects the opening of the throttle valve, and the amount of fuel supplied to the internal combustion engine is controlled according to the load state of the internal combustion engine. An output control device for an internal combustion engine, comprising: an accelerator pedal angle sensor, the throttle valve opening sensor, and the step motor. An abnormality detecting means for detecting at least one of the abnormalities, and when the abnormality is detected by the abnormality detecting means, the fuel supply control means is provided when the engine speed exceeds a predetermined engine speed determined according to the output of the accelerator pedal angle sensor. A fuel cutoff control means for shutting off the fuel supply by means of: and a predetermined opening smaller than the opening set by the target throttle valve opening setting means when an abnormality is detected by the abnormality detection means, as the target throttle valve opening. The output control device of the internal combustion engine is provided with the abnormal throttle valve opening setting means.

When the abnormality detecting stage detects an abnormality,
When the engine speed exceeds a predetermined engine speed determined according to the output of the accelerator pedal angle sensor, the fuel cutoff control means cuts off the fuel supply, and the abnormal throttle valve opening setting means opens the target throttle valve opening at a predetermined small opening. Since it is set every time, it is possible to drive in a restricted state.

[0009]

EXAMPLE An example of the present invention shown in FIGS. 1 to 11 will be described below. FIG. 1 is a system configuration diagram of fuel supply control and intake system throttle valve opening control in an electronic control unit ECU that controls the operation of an internal combustion engine.

In the internal combustion engine of this embodiment, the amount of fuel supplied is controlled by controlling the drive of the fuel injection valve, and the throttle valve 1 is driven by the step motor 2 in accordance with the depression amount of the accelerator pedal.

The swing angle of the accelerator pedal is detected by an accelerator pedal angle sensor using a potentiometer. Two accelerator pedal angle sensors are prepared, and the detection signals AP1 _S from the accelerator pedal angle sensors 3 and 4 are provided. , AP2 _S is output. This is adopted to improve the reliability of the accelerator pedal angle sensor, and the opening of the throttle valve 1 is detected by the throttle valve opening sensor 5 to monitor the abnormality of the throttle valve control system. Is used for. The opening of the throttle valve 1 is detected by the throttle valve opening sensor 5 and fed back.

The fuel supply control in the ECU is FI
-The CPU 10 is in operation, and the FI-CPU 10 receives detection signals from various sensors that detect the operating state of the internal combustion engine. For example, the intake pipe absolute pressure P _B , the engine speed N _E , the vehicle speed V, etc. Accelerator pedal angles AP1 _S and AP2 _S from the angle sensors 3 and 4 and the throttle valve opening sensor 5 and the throttle valve opening TH _S
Are input, and an INJ signal for controlling the fuel injection valve and an IG signal for controlling the ignition timing are output via the gate 6 based on the operating state.

On the other hand, the throttle valve opening control is performed by DBW-CP.
U11 performs the operation, and the signals of the accelerator pedal angles AP1 _S and AP2 _S from the accelerator pedal angle sensors 3 and 4 and the throttle valve opening TH _S signal from the throttle valve opening sensor 5 are input to the step motor. Two
The signals of the excitation phase φ and the duty D for driving are output to the step motor drive circuit 7, and the step motor drive circuit 7 drives the step motor 2.

Since the FI-CPU 10 contains information from various sensors, the accelerator pedal angles AP1 _S , A
Normal throttle opening TH _NML , vehicle speed V based on P2 _S
Based on the throttle opening TH _CRU during auto cruise,
Throttle opening TH _IDL at idle based on engine speed N _E , throttle opening TH _TCS at traction control based on vehicle speed V and drive wheel speed, throttle opening TH _INH at engine output limit, etc. Is calculated, and these pieces of information are stored in the DB through the DP-RAM 12 which exchanges signals between the FI-CPU 10 and the DBW-CPU 11.
It is transmitted to the W-CPU 11.

The DBW-CPU 11 determines the final target throttle opening TH _O based on this information, and sets the throttle valve 1 to the target throttle opening TH _O under the driving condition of the step motor. The excitation phase φ and the duty D of the current supplied to the motor 2 are set and output. FI-C may be used depending on operating conditions or abnormal conditions.
The PU 10 side can intervene in the DBW-CPU 11 to enter the backup, and at this time, the communication by the DP-RAM 12 is stopped.

In the above control system, DB
The main routine of the W-CPU 11 will be described with reference to FIG.
First, the signals from various sensors and the information input from the FI-CPU 10 via the DP-RAM 12 are read (step 1), and then there is no abnormality in the accelerator pedal angle sensors 3 and 4 (step 2). It is checked whether or not the sensor 5 is abnormal (step 3).
Then, the fully closed state of the throttle valve is checked and the zero point is updated (step 4), the movement of the throttle valve is checked (9 DEG check) (step 5), and then the presence or absence of step out of the step motor 2 is detected. (Step 6).

The various checks from step 2 to step 6 will be described later, but if any one of them is detected to be abnormal, the fail safe flag F _{FS is set} to "1".
Stands.

Then, in the next step 7, it is determined whether or not the initialization flag F _INIT is "1". If "1" is not set, the predetermined check has not been completed yet, so the process jumps to step 15. If "1" is set, it proceeds to the next step 8 to determine whether the FI-CPU 10 is in the backup, and if it is in the backup,
It adopted towards its greater than the minimum throttle opening TH _IDLFS when the throttle opening TH _AP idle easily determine the target throttle opening degree TH _O in accordance with the accelerator pedal angle (Step 10).

If the FI-CPU 10 is not in the backup in step 8, it is judged whether the DP-RAM 12 can be used (step 9).
Proceed to step 10 and, if possible, proceed to step 11 and proceed to DP-RA
Various throttle opening TH _NML , T input via M12
The final target throttle opening TH _O is determined from H _CRU , TH _IDL , TH _TCS and TH _INH .

Next, at step 12, it is judged whether or not "1" is set in the fail-safe flag F _FS. If not, it means that there is no abnormality in the throttle control system and the process jumps to step 15. If "1" stands, there is an abnormality in the throttle control system and the process proceeds to step 13. First, it is determined whether the target throttle opening TH _O exceeds the upper limit TH _FS. If so, the upper limit value TH _FS is set to the target throttle opening TH _O (step 14).

That is, when there is an abnormality in the throttle system (F _FS = 1), an upper limit is set on the target throttle opening to regulate it. This upper limit value TH _FS is a low value, for example, 10 ° to 15
The value is °.

[0022] In step 15, controls the driving of the step motor 2 so as to be determined target throttle opening degree TH _O. Although detailed description of the drive control of the step motor will be omitted here, the stored value is stored as a current position in a memory that increments / decreases by 1 each time the throttle opening is opened or closed by one step. Opening TH
The open-loop control of the step motor is adopted in which whether the current step drive is valve opening or valve closing is selected depending on the magnitude relation of ₀ and at the same time the current stored throttle opening is stepped.

On the other hand, fuel cut control is performed on the FI-CPU 10 side, and its control routine will be described with reference to FIG. First, it is determined whether or not any abnormality has occurred in the two accelerator pedal angle sensors 3 and 4 (step 21). This abnormal information is sent to DBW via DP-RAM12.
-It is input from the CPU 11.

When it is determined that both accelerator pedal angle sensors 3 and 4 are abnormal, the _routine jumps to step 22 and the upper limit N _{FCAP is} set to the fuel cut threshold N _FC of the engine speed.
(For example, 1500 RPM) is entered and the low speed is used as the fuel cut threshold.

When it is judged at step 21 that at least one of the accelerator pedal angle sensors 3 and 4 is not abnormal, the routine proceeds to step 23, where the fail safe flag F _{FS is given.}
It is determined whether or not "1" is set. If it is not set, it means that the throttle control system is normal, so the process jumps to step 26, and an appropriate value N _{FCN is} determined based on the engine water temperature and other operating conditions.
Is set, and this is set as the fuel cut threshold N _FC (step 27). This fuel cut threshold is set to the over-rev prevention rotation speed that is provided to prevent mechanical destruction of the engine after the engine is warmed up, and the fuel cut rotation is accompanied by an increase in engine temperature to prevent overheating of the engine. It is set to reduce the number (step 27). When at least one of the accelerator pedal angle sensors 3 and 4 is normal and the fail safe flag F _{FS is set} to "1",
There is something wrong with the throttle control system. At this time, the routine proceeds to step 24, where the predetermined engine speed N _FCFS according to the accelerator pedal angle TH _AP based on the normal accelerator pedal angle sensor is determined from the table shown in FIG. This is searched and this N _FCFS is set as the fuel cut threshold N _FC (step 25).

[0026] Thus-determined by comparing the fuel cut-off threshold N _FC and the actual engine speed N _E (step 28), when the actual engine speed N _E exceeds the fuel cut-off threshold N _FC Performs fuel cut (step 30), cuts off the fuel supply from the fuel injection valve, and maintains the fuel supply if it does not exceed (step 2)
9).

Therefore, even when there is an abnormality in the throttle control system (F _FS = 1), the fuel cut is performed only when the engine speed N _E exceeds the fuel cut threshold N _FC determined according to the normal accelerator pedal angle. And then
If it does not exceed the limit, it is possible to continue running at a low engine speed without performing fuel cut.

In FIG. 11 showing the search table, the horizontal axis is the accelerator pedal angle TH _AP and the vertical axis is the engine speed N.
_The broken line indicates the fuel cut threshold N _FCFS . A constant engine speed is fixed at a large value as the small value of TH _AP and fuel cut threshold, and the fuel cut threshold engine speed which is substantially proportional to TH _AP in between. Therefore, the fuel cut threshold value that is proportional to the normal TH _AP is set, and TH _{AP that} exceeds a certain value is set.
Becomes larger, a certain fuel cut threshold is set.

Therefore, even if an abnormality occurs in the throttle control system and a large amount of intake air continues to be supplied, fuel is supplied in accordance with the accelerator pedal angle within a rotational speed region where the engine rotational speed N _E is somewhat low.

Next, the check steps 2, 3, 4, 5 and 6 for detecting an abnormality of the throttle control system for determining the fail safe flag F _FS will be described in detail in order.

First, the check routine of the accelerator pedal sensor corresponding to step 2 will be described with reference to FIGS. 4 and 5. In step 41 and step 42 of FIG. 4, the abnormality of the first accelerator pedal angle sensor 3 and 4 is determined, respectively, and since the same processing is performed in both, the abnormality determination of the first accelerator pedal angle sensor 3 is determined. Only the routine is shown in FIG. 5, which will be described below with reference to FIG.

In step 61, the accelerator pedal angle is read as a digital value AP1 _AD , and it is determined whether or not the first accelerator pedal angle sensor abnormality (AP1 abnormality) flag F _{AP12 is set} to "1" (step 62). Since "1" has not risen, the routine proceeds to the next step 63, where the detected value AP1 _{S of} the first accelerator pedal angle sensor 3 is the upper limit AP _FSH.
It is determined whether or not the value exceeds the value. If the value exceeds the value, jumping to step 69 means that there is a risk of disconnection or short circuit. If not, the operation proceeds to step 64. This time, the detected value of the first accelerator pedal angle sensor 3 is detected. AP1 _S is the lower limit value AP _FSL
It is determined whether or not the value is less than 1., and if it is less than that, there is a risk of short circuit, and the process jumps to step 69. If it is less than that, there is no risk of disconnection or short circuit, and the process proceeds to step 65.

In step 65, the normal detected value AP1 _S of the first accelerator pedal angle sensor 3 is set to the accelerator pedal angle AP1 _AD , the abnormal provisional flag F _AP1MS is set to "0" (step 66), and the timer T is set. set to T ₁ to _AP1 (step 67), first AP1 abnormality flag F
_{AP11 is set} to "0", and in the next step 76, AP1 _AD is converted to the first accelerator pedal angle AP1 based on the accelerator pedal angle during idling.

On the other hand, if there is a risk of disconnection or short circuit in steps 63 and 64, jump to step 69 and set "1" to the AP1 abnormality provisional flag F _AP1MS to determine whether or not the timer T _AP1 has timed out ( Step 70), jump to Step 75 until the time is up, and 1 when the time is up
It is determined whether or not "1" is set in the AP1 abnormality flag _FAP11 for the second time (step 71). Since "1" is not initially set, the process proceeds to step 72 and the timer T _AP1 is set to T again.
Set to ₁ and set "1" to the AP1 abnormality flag _FAP11 for the first time (step 73).

Then, as the accelerator pedal angle AP1 _AD , a predetermined angle AP ₀ close to the fully closed position is set (step 7).
Five). Still when a disconnection or short circuit persists, repeat the step 63 or 64,69,70,75, timer T _AP1
When the time went up, step 70 to step 71
Since the first AP1 abnormality flag F _AP11 has already been set to "1", the process jumps to step 74 and the second A
The P1 abnormality flag _FAP12 is set to "1".

This second AP1 abnormality flag F _AP12 finally becomes a flag indicating an abnormality of the first accelerator pedal angle sensor 3. Note that the accelerator pedal angle AP1 _AD is set to the small angle AP ₀ both when the abnormality is provisionally in the abnormal state and when the abnormality is confirmed (step 75).
It is then converted to AP1 (step 76).

The above is the AP1 abnormality determination routine.
By the same processing, the second accelerator pedal angle sensor 4
AP2 abnormality determination is performed for (step 4 in FIG. 4).
2) If the accelerator pedal angle AP2 is determined and the vehicle is provisionally in an abnormal state, the AP2 abnormality provisional flag F
"1" Standing in _AP2MS, "1" stands in AP2 abnormality flag F _AP22 If the abnormality is determined.

After determining the abnormality of the first and second accelerator pedal angle sensors 3 and 4 in this way, the process proceeds to step 43 of FIG. 4 to determine whether "1" is _set in the AP1 abnormality provisional flag F _AP1MS . If it is determined that “1” is set, there is a possibility that the first accelerator pedal angle sensor 3 is abnormal, and the process jumps to step 50, and the second accelerator pedal angle sensor 4 is set as the accelerator pedal angle AP for the subsequent control. The base angle AP2 is adopted (step 50).

When there is a possibility that the second accelerator pedal angle sensor 4 is also abnormal, AP2 already has an angle AP ₀ close to fully closed. Therefore, if AP2 is adopted in step 50, it is finally selected. Further, the accelerator pedal angle AP is set to a predetermined angle AP _{0 that} is close to full closing.

Also, there is no fear of abnormality in the first accelerator pedal angle sensor 3, and the second accelerator pedal angle sensor 4
If there is a problem with the
Proceed to step 49 through 44, and there is no danger of abnormality.
The angle AP1 based on the accelerator pedal angle sensor 3 is set to the accelerator pedal angle AP. When there is an abnormality in at least one of the first accelerator pedal angle sensor 3 and the second accelerator pedal angle sensor 4 as described above, the routine proceeds from step 49 or step 50 to step 56.

On the other hand, the first accelerator pedal angle sensor 3,
If there is no risk of disconnection or short circuit in 4 above, the routine proceeds to step 45, where it is judged if AP1 is larger than AP2 by a difference of the allowable value D _AP or more.
Go to step 2 to select the smaller AP2 as the accelerator pedal angle AP, and if not, go to step 46, this time AP
It is determined whether or not 1 is smaller than AP2 by the allowable value D _AP or more. If it is smaller, the process proceeds to step 48, and the smaller AP1 is selected as the accelerator pedal angle AP, and if it is not significantly different, the process proceeds to step 49. , AP1 is selected as the accelerator pedal angle AP.

That is, the difference between AP1 and AP2 is the allowable value D.
If it exceeds _AP , there is a relative abnormality, and the smaller one is selected as the accelerator pedal angle AP. At this time, the routine proceeds to step 51.

If the difference between AP1 and AP2 is smaller than D _AP , the first and second accelerator pedal angle sensors 3, 4
Since there is no difference in the detected values and there is no relative abnormality and it is normal, at this time, AP1 is always adopted as the accelerator pedal angle AP, and the routine proceeds to step 56 as the next step. In step 56, the second relative abnormality flag F
It is determined whether or not "1" is set in _NGAP2 . Initially, "1" is not set. Therefore, the process proceeds to step 57 and "0" is _set in the first relative abnormality flag F _NGAP1 and the up timer T _NG is reset. Yes (step 58). Note that F _NGAP2 =
If it is 1, jump from step 56 to step 58.

When the difference between AP1 and AP2 becomes large and a relative abnormality is recognized, the routine proceeds to step 51, where it is judged whether or not the up timer T _NG has _{exceeded the} predetermined time T ₂ .
If it is within the predetermined time T ₂ , the first relative abnormality flag F
_Determine whether "1" is set in _NGAP1 (step
52) In the state where "1" is not initially set, "1" is set to the first relative abnormality flag F _NGAP1 (step 52) and the up timer T _NG is reset (step 54).

At step 52, the first relative abnormality flag F
_When "1" is already set in _NGAP1 , the process jumps to step 55, and "1" is set in the second relative abnormal flag F _NGAP2 . That is, first the relative abnormality predetermined time T ₂ continues 1
When the relative abnormality flag F _NGAP1 for the _second time is set to "1" (step 53), and the relative abnormality T ₂ continues for a predetermined time, the relative abnormality flag F _NGAP2 for the second time is set to "1" (step 55). The second relative flag F _NGAP2 finally becomes a flag indicating a relative abnormality between the first accelerator pedal angle sensor 3 and the second accelerator pedal angle sensor 4.

When the accelerator pedal angle sensor check routine is completed and an abnormality is found in the first accelerator pedal angle sensor 3, the AP1 abnormality flag F _{AP12 is detected.}
When the first accelerator pedal angle sensor 4 is abnormal and the second accelerator pedal angle sensor 4 is abnormal, the AP2 abnormality flag _FAP22 is set to 1 and the first and second accelerator pedal angle sensors 3 and 4 are relatively abnormal. When it is recognized, “1” is set in the relative abnormality flag F _NGAP2 .

Next, the throttle sensor check routine corresponding to step 3 in FIG. 2 will be described with reference to FIG. First, at step 81, the counters C _FS and C _NG are set to predetermined values C ₁ and C ₂ , and the throttle opening is set to a digital value T.
It is read as H _AD (step 82), and then it is judged whether or not the detected value TH _S of the throttle valve opening sensor 5 exceeds the upper limit value TH _FSH (step 83). So jump to step 87,
If it does not exceed, the routine proceeds to step 84, this time it is judged whether or not the detected value TH _S of the throttle valve opening sensor 5 is below the lower limit value TH _FSL . If it is below, there is a risk of disconnection and jump to step 87. If it is not below, there is no risk of disconnection or short circuit, and the process proceeds to step 85.

At step 85, the detected value TH _S of the throttle valve opening sensor 5 is set to the throttle opening TH _AD , and the routine proceeds to step 86, at which this throttle opening TH _AD exceeds a predetermined value TH _CLS close to fully closed. It is determined whether or not there is. Initially, the step motor 2 is entered into the check routine.
No electric current is applied to the throttle valve 1, and the throttle valve 1 should be fully closed by the return spring. If normal, the throttle opening TH _AD shows a value smaller than TH _CLS, and the routine exits from step 86 as it is. If, on the other hand, shows a large value, it means that there is a possibility of characteristic abnormality, and therefore the routine proceeds to step 92.

If there is a risk of disconnection or short circuit in steps 83 and 84, the process proceeds to step 87, the counter C _FS is decremented, and it is determined whether C _FS becomes "0" (step 88). , Return to step 82.

Steps 82, 83 (84), 87 and 88 are repeated as long as the possibility of disconnection or short circuit continues. When the counter C _FS is decremented to "0", the process moves from step 88 to step 90 and the throttle sensor The abnormality (TH abnormality) flag F _FSTH is set to "1" to confirm the abnormality, and the throttle opening TH _AD is set to a predetermined value TH ₁ of low opening for the time being (step 91).

Further, there is no fear of disconnection or short circuit, but there is a possibility of characteristic abnormality, that is, when the throttle opening TH _AD exceeds a predetermined value TH _CLS close to full closure (current flows through the step motor 2 during this check routine). If it is normal, the throttle valve 1 should be fully closed by the return spring.) Step 86 to step
The routine proceeds to 92, where the counter C _NG is decremented, and it is determined whether or not C _NG has become "0" (step 93), the routine returns to step 82, and the following steps 82, 83, 84, 85, 86, 92, 93.
repeat.

Then, when the counter C _NG becomes "0", the routine proceeds from step 93 to step 94, and "1" is set to the first-time fully closed abnormality flag F _ZRTH1 . The first full-closed abnormality flag F _ZRTH1 is a flag that temporarily sets "1" when there is a possibility of full-closed abnormality, and a flag indicating the confirmation of abnormality is performed by a zero point update routine which will be described later.

Next, the throttle zero point updating routine corresponding to step 4 in FIG. 2 will be described with reference to FIGS. 7 and 8. First, it is judged whether or not the zero point updated flag F _ZRCK is _set to "1" (step 101). Since the zero point has not been updated at the beginning, the _routine proceeds to step 102, at which the current supplied to the step motor 2 is driven. _{Put a} predetermined initial duty value D _MINIT into the duty D _MOV and set the duty D
_A predetermined initial duty value D _HINIT is set in _HLD (step 103), and a predetermined low frequency TM _OL is set in drive frequency TM ₀ (step 104).

Then, in the next steps 105 and 106, when there is an abnormality in the drive current supplied to the step motor 2, flags F _COM1 and F _COM2 are set to "1" in a subroutine (not shown).
If the status is "1" and the status is "1", step 11
After jumping to 0, the zero point updated flag F _ZRCK is set to “1” and thereafter the zero point is not updated.

If there is no abnormality in the drive current of the step motor 2, the routine proceeds to step 107, where the TH abnormality flag F _FSTH is set to "1" when there is an abnormality of disconnection or short circuit in the throttle sensor check routine. ,
If "1" is set, the process jumps to step 108 to excite the 1st and 4th phases of the step motor 2, set 1 and 4 phase excitation flag Fφ _1.4 to "1" (step 109), and further set the zero point. Zero is not updated after the updated flag F _ZRCK is set to "1". It should be noted that the reference throttle opening close to the fully closed state is maintained by the 1- and 4-phase excitation. The reference throttle opening is an opening that is adjusted so as to match a predetermined design opening when the throttle valve and the step motor are assembled in a 1-, 4-phase excitation state, and is a throttle that maintains the idle speed of the engine. The opening is lower than the opening.

If "1" is not set in the TH abnormality flag F _FSTH in step 107, it proceeds to step 111 and it is judged whether or not "1" is _set in the first full-closed abnormality flag F _ZRTH1. If you jump to step 131 in Figure 8,
If "1" is not set, the process proceeds to the next step 112.

In step 112, the 1 and 4 phase excitation completion flag F
Determine the condition of φ _1.4 , and if “1” is not standing, 1,
Excitation of 4 phases (step 113), 1st and 4th phase excitation completed flag F
Set "1" to φ _1.4 (step 114), counter C _ZR
A predetermined count value C _ZR1 is set to (step 115).

Therefore, after that, the step motor 1
Steps 112 to 116 with four phases excited
Then, it is judged whether or not the throttle opening TH _AD exceeds a predetermined opening TH _CLS close to the fully closed state.

The throttle opening TH _AD is the predetermined opening TH
If it is smaller than _CLS , the throttle valve 1 is in the vicinity of fully closed and is normal, and this throttle opening TH _AD is the zero-point reference opening, and the conversion value TH _ZR is calculated (step
117), "1" is set to the zero point updated flag F _ZRCK (step 118), and this routine is finished. After that, an accurate stroke opening can be obtained by using the difference between the AD value of the sensor and the zero point reference opening as the throttle opening.

On the other hand, in step 116, the throttle opening TH _AD
When the value exceeds the predetermined opening TH _CLS , there is a possibility of a full-closed abnormality, so the routine proceeds to step 119, where the counter C _ZR is decremented and it is judged whether or not C _ZR becomes “0”. (Step 120) If the full-closed abnormality continues until C _ZR becomes "0", the routine proceeds to step 121, where "1" is set to the first full-closed abnormality flag F _ZRTH1 . The steps of the throttle sensor check routine
Also in 94, "1" may be set in the first full-closed abnormality flag F _ZRTH1 .

When "1" is set in the first full-closed abnormality flag F _ZRTH1 on the _assumption that there is a possibility of full-closed abnormality in this way, the process jumps from step 111 to step 131 in FIG. 8 and the return spring checked flag F _RSPCK is set. determine the state, since initially not set to "1", the stored throttle opening SM proceeds to step 132 is calculated from the throttle opening degree TH _AD, sets "0" to the target throttle opening degree TH _O (step 133), the step motor 2 is driven back.

That is, when there is a possibility that the throttle valve 1 will be fully closed, the step motor 2 is driven so that the current throttle opening TH _AD is once set as the stored throttle opening SM and the target throttle opening is 0 degree. .

Then, the return spring checked flag F _RSPCK is set to "1" (step 134), and thereafter, the _routine proceeds from step 131 to step 135, and it is memorized whether or not the return drive is completed, and the throttle opening SM and the target throttle opening are stored. It is determined whether SM _CMD, which is the difference in opening, has become "0". When it has become "0", the routine proceeds to step 136, where the state of the 1 and 4 phase excited flag Fφ _1.4 is confirmed, and "1" is If not standing, proceed to step 137 to excite the 1st and 4th phases and
"1" is set to the phase excitation flag Fφ _1.4 (step 13
8) Then, a predetermined count value C _ZR1 is set in the counter C _ZR (step 139).

After that, the routine proceeds from step 136 to step 140, and it is judged again whether or not the throttle opening TH _AD exceeds a predetermined opening TH _CLS close to full closure. If not, the characteristic of the step motor 2 is normal. And step 14
The routine proceeds to 1 and the full-closed abnormality flag F _ZRTH1 for the first time is returned to "0" to calculate the zero-point reference opening TH _ZR (step 142).
The reason why the full-closed abnormality may have occurred before is not because of the characteristic abnormality of the step motor 2 but because of the possibility of abnormality of the return spring. The return spring abnormality flag _FRSP1 is set to "1" (step 144). The zero point updated flag F _ZRCK is set to "1" (step 145) and the zero point update routine is terminated.

On the other hand, in step 140, the throttle opening TH _AD
Is above the predetermined opening TH _CLS , step 14
Decrements the counter C _ZR proceeds to 5, C _ZR is determined whether it is "0" (step 146), the C _ZR is "0" and fully closed abnormality persists until, step
_Proceeding to step ₁₄₇ , "1" is set to the second full-closed abnormality flag F _ZRTH2, and "0" is _set to the return spring abnormality flag F _RSP1 as the characteristic abnormality of the step motor 2 and not the abnormality of the return spring (step 148 ), The zero point updated flag F _ZRCK is set to "1" (step 144), and the zero point updating is completed.

As described above, in the throttle zero point update routine, if there is a fully closed abnormality during the zero point update of the characteristics of the step motor 2, "1" is set to the second fully closed abnormality flag F _ZRTH2. .

Next, a 9-degree check routine for checking the operation of the step motor 2 (corresponding to step 5 in FIG. 2) will be described with reference to FIG. First, the state of the initialization flag F _INIT is determined (step 151), and since "1" is not initially set, the process proceeds to step 152 and the state of the zero point updated flag F _ZRCK is determined, and when the zero point update is completed. Advances to step 153 and determines whether SM _CMD is "0". In addition, "1" is set to the initialization flag F _INIT.
If it is set, the routine proceeds to step 171, where the FI injection prohibition flag F _INJINH is set to "0" and this routine is finished.

If the zero point update is not completed, or if SM _CMD is not "0" even if the zero point update is completed, this routine is exited. Zero has been updated SM
_CMD is "0", the process proceeds to step 154, the target throttle opening degree TH _O in corresponding 9 degrees from the fully closed reference throttle opening degree in the opening direction of (the opening degree of when the next 1,4-phase excitation state) The predetermined opening TH _CK is set, and the 9-degree check passage flag F
The state of _9DCK is discriminated (step 155), and since it is initially "0", the process proceeds to step 156 where the 9-degree check passage flag F _9DCK is set to "1" and the predetermined count value C _9D1 is set to the counter C _9D. Set and exit this routine

Therefore, after that, steps 155 to 15
Proceed to step 8 and determine the status of the TH abnormal flag F _FSTH , and set to "1"
If is standing, it means that there is something wrong with the throttle sensor 5, so you can't check it 9 times.
After skipping to 3, the initialization flag F _INIT is set to "1", and thereafter, the 9th check routine is not performed. On the other hand, if the throttle sensor 5 is normal, proceed to step 159 to determine whether or not the zero-point reference opening TH _ZR has been calculated. If the calculation is not completed, the accurate stroke angle cannot be determined, so check 9 degrees. Since this cannot be done, the initialization flag F _INIT is set to "1" and the routine exits.

If the zero point reference opening TH _ZR has been calculated, the routine proceeds to step 160, where the throttle opening TH is the upper limit value TH.
_Determine whether it exceeds _CKH (equivalent to 10 degrees, for example),
If it does not exceed, then it is determined whether or not it is below the lower limit TH _CKL (equivalent to 8 degrees, for example) (step 161).
That is, it is normal if the throttle opening TH is between the upper limit value TH _CKH and the lower limit value TH _CKL . In this _case , the _routine proceeds to step 162, where the first 9-degree abnormality flag F _9DTH1 is _set to "0", and the initialization flag is set. This routine is ended by setting "1" to F _INIT .

On the other hand, the throttle opening TH is the upper limit value TH _CKH.
When either below the exceeded or the lower limit value TH _CKL the decrements the counter C _9D proceeds to step 164 as there is abnormal fear to the operation of the step motor 2, C _9D abnormal operation until "0" If the problem is not solved, proceed to step 166, and the 9th abnormality flag F for the first time.
_9DTH1 status is discriminated. Initially it is “0”, so step
Proceed to 167 and set "1" to the 9th abnormal flag F _9DTH1 for the first time.
The stand, then set to "0" to the target throttle opening degree TH _O (step 168), once performed drive returns the stepping motor 2 is fully closed, the nine-time check flag F _9DCK to perform the re-9 degrees check " It is set to 0 "(step 169).

The step motor 2 is driven again to the degree equivalent to 9 degrees, and the throttle opening TH is still set to the upper limit value TH _CKH and the lower limit TH.
_If it is not between _CKL , wait for the counter C _9D to reach "0" (step 165), and proceed to step 166. This time, the 9th abnormality flag F _9DTH1 for the first _time is "1". Therefore, the process proceeds to step 170 and the second 9-degree abnormality flag F
Set a "1" in _9DTH2, make a to "1" to the initialization flag F _INIT (step 163), and terminates this routine. As described above, in the 9-degree check routine, when an abnormality is recognized in the operation of the step motor 2, "1" is set to the second 9-degree abnormality flag _F9DTH2 .

Next, the step-out detection routine for the step motor 2 (corresponding to step 6 in FIG. 2) will be described with reference to FIG. First, the state of the step-out flag F _DAC is determined (step 181). Since "1" is not initially set, step
Proceed to step 182, determine the state of the initialization flag F _INIT , and if the zero point update and 9-degree check are not completed (F _INIT = 0), exit this routine, and if completed, proceed to the next step motor error flag. The state of F _SMFS is determined. Since it is not "1" at the beginning, the routine proceeds to step 184, and the state of the throttle sensor abnormality flag F _FSTH is determined. If there is an abnormality in the throttle sensor, this routine is exited, and if there is no abnormality, step 185 Then, the process proceeds to step _{S31 and} the state of the characteristic abnormality flag F _NGTH of the step motor 2 is determined.

[0074] The characteristic abnormality flag F _ngth is a "1" is abnormal characteristics of the step motor 2 stand when the the "1" in at least one of total閉異normal flag F _ZRTH2 and 9 degrees abnormality flag F _9DTH2 standing It is a flag that indicates. Therefore, when "1" is _set in the characteristic abnormality flag F _NGTH , step-out detection cannot be performed and the routine exits.

If there is no characteristic abnormality in the step motor 2, the process proceeds to step 186, and whether the difference between the throttle opening TH based on the throttle valve opening sensor 5 and the presently stored throttle opening SM exceeds a predetermined angle (4.5 degrees). It is determined whether or not. This is because at the time of step out, the excitation state is in the same phase as the target throttle opening degree currently instructed, so at least
This is set to this angle because it is sufficient to deviate by more than half the angle to detect this. If this predetermined angle is not exceeded, it is normal, and the routine proceeds to step 188, where the out-of-step counter C _ER is cleared and this routine exits.

On the other hand, in step 186, | TH-SM |> 2
In the case of _DH , there is a risk of step out, so again step 19
Go to 0 and count the out-of-step counter C _ER . If the step-out counter C _ER exceeds the predetermined count value C _EI and the possibility of step-out continues, the routine proceeds to step 192, where the step-out flag F _DAC is set to "1" and the abnormality determination timer T
_It is determined whether the _DAC is finished.

Initially, the abnormality determination timer T _DAC has expired, and the routine proceeds to step 194, where the out-of-step occurrence counter C
_{The DAC} is cleared and the abnormality determination timer T _DAC is reset (step 195).

If the step out occurs again after the abnormality determination timer T _DAC is reset and started before the timer T _DAC ends, the process jumps from step 193 to step 196, and one or three of the excitation phases of the step motor 2 Whether there is an abnormality in the drive circuit is determined from the state of the 1 and 3 phase abnormality flag F _13FS. If there is an abnormality, this routine is exited. determine the state of 2,4-phase abnormality flag F _24FS, if any abnormality exits the routine counts the desynchronization occurrences counter C _DAC proceeds to step 198 when there is no abnormality, the next step 19
At 9 it is judged whether the count value C _DAC has become equal to or greater than the predetermined value C _D1. Until it reaches C _D1 , the routine proceeds to step 195 and the abnormality judgment timer T _DAC is reset again.

[0079] The abnormality determination timer T or a look at the step-out again in the _DAC occurs, count the out-of-occurrence number counter C _DAC if the occurrence, and repeatedly step out and continue to generate this C _DAC is Predetermined value C with increasing gound value
_{If D1} is exceeded, step-out frequently occurs and no correction can be seen. Therefore, in step 200, the step motor error flag F _SMFS
Then, "1" is set to end this routine.

As described above, in the step motor step-out detection routine, "1" is set in the step motor abnormality flag F _SMFS when step-out occurs frequently.

[0081] or the accelerator pedal angle sensor abnormality flag F _{AP 12} in the accelerator pedal check routine as described in detail, F _{AP 22,} relative abnormality flag F _NGAP2, throttle sensor abnormality flag F _FSTH in the throttle sensor checking routine, the throttle zero update routine All閉異normal flag F _ZRTH2, 9 ° 9 ° abnormality flag F in the check routine _9DTH2, even one "1" of the flag indicating the abnormality of the above throttle control system of the step motor abnormality flag F _SMFS in step-out detection routine When it is set, "1" is set in the fail safe flag F _FS , and the target throttle opening TH _O is regulated by setting a low predetermined upper limit value TH _FS (steps 13 and 14 in FIG. 2) and the normal accelerator pedal angle is set. Engine speed N _F according to throttle opening TH _AP based on Search _CFS table (Fig. 3
Step 24) is set to the fuel cut threshold N _FC (Step 25), and when the engine speed N _E exceeds this fuel cut threshold, fuel cut (Step 30),
If not exceeded, fuel supply continues (step 29)
Therefore, even if an abnormality occurs in the throttle control system, it is possible to maintain a certain degree of travel, and emergency travel and home travel are possible.

[0082]

According to the present invention, in an internal combustion engine in which a throttle valve is driven by a step motor, when an abnormality occurs in the throttle valve control system, the target throttle opening is limited in a state where the throttle valve can be driven, Since the fuel cut is controlled appropriately regardless of the opening degree of the throttle valve, it is possible to reliably prevent the engine output from unexpectedly increasing.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of an embodiment according to the present invention.

FIG. 2 is a flowchart showing a main routine of a DBW-CPU.

FIG. 3 is a flowchart showing a fuel cut control routine of the FI-CPU.

FIG. 4 is a flowchart showing an accelerator pedal sensor check routine.

FIG. 5 is a flowchart showing an AP1 abnormality determination routine.

FIG. 6 is a flowchart showing a throttle sensor check routine.

FIG. 7 is a flowchart showing a throttle zero point updating routine.

8 is a continuation of the flowchart shown in FIG.

FIG. 9 is a flowchart showing a 9-degree check routine.

FIG. 10 is a flowchart showing a step motor step-out detection routine.

FIG. 11 is a diagram showing a fuel cut threshold value.

[Explanation of symbols]

1 ... Throttle valve, 2 ... Step motor, 3 ... 1st accelerator pedal angle sensor, 4 ... 2nd accelerator pedal angle sensor, 5 ... Throttle valve opening sensor, 6 ... Gate, 7 ... Step motor drive circuit, 10 ... FI -CPU,
11 ... DBW-CPU, 12 ... DP-RAM.

Claims (2)

[Claims] 1. A throttle valve provided in an intake passage of an internal combustion engine, an accelerator pedal angle sensor for detecting a depression angle of an accelerator pedal, and a target throttle valve opening degree determined according to an output of the accelerator pedal angle sensor. Target throttle valve angle setting means, a drive circuit that drives the throttle valve based on the target throttle valve opening, a step motor that controls the supply current by the drive circuit to open and close the throttle valve, and the throttle valve An output control device for an internal combustion engine, comprising: a throttle valve opening sensor for detecting the opening of the internal combustion engine; and a fuel supply control means for controlling the amount of fuel supplied to the internal combustion engine according to the load state of the internal combustion engine, Abnormality detecting means for detecting an abnormality in at least one of the accelerator pedal angle sensor, the throttle valve opening sensor, and the step motor; When an abnormality is detected by the abnormality detection means, a fuel cutoff control means for shutting off the fuel supply by the fuel supply control means when the engine speed exceeds a predetermined engine speed determined according to the output of the accelerator pedal angle sensor; and the abnormality detection means. When an abnormality is detected by the above, an abnormal throttle valve opening setting means for setting a predetermined opening smaller than the opening set by the target throttle opening setting means to the target throttle opening is provided. A characteristic output control device of an internal combustion engine. 2. The internal combustion engine according to claim 1, wherein the abnormal throttle valve opening setting means is provided with a throttle valve control CPU, and the fuel cutoff control means is provided with a fuel control CPU. Output control device.