JPH0660587B2 - Fail-safe system in engine control system - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fail-safe system mainly applied to an engine control system of a vehicle.

[Prior Art] In recent years, many engine engines for automobiles are designed to perform idle speed control in order to improve fuel economy. That is, in this idle speed control, an opening adjustment mechanism for adjusting the closed position of the throttle valve of the carburetor is provided, and the actual engine speed converges to the target speed in the operating region considered as idling. As described above, the operation of the opening degree adjusting mechanism is controlled. Then, the target rotational speed is updated in accordance with the cooling water temperature of the engine, etc., so that the idle rotational speed can be stably maintained at a value as low as possible within a range in which engine stall is not caused.

In addition, there is also a study to utilize the opening adjustment mechanism to perform throttle opening control before starting and quick idle-up control at the time of complete explosion or when the air conditioner is on.

By the way, it is necessary to successively supply the actual throttle opening detected by the throttle opening detecting means as one input information to the valve closing position control means for controlling the operation of the opening adjusting mechanism. When the throttle opening control means fails, it becomes impossible to control the closed position of the throttle valve to an appropriate position, which may lead to engine stall. Therefore, it is necessary to provide a fail-safe system as a countermeasure against such a failure.

As a prior art of such a fail-safe system, as shown in JP-A-58-217744, when the throttle opening detection means fails, the auxiliary air amount control means is operated up to the operation limit. There is one that can prevent engine stall.

However, this system is not a system that is configured in consideration of the fuel cut system, and therefore, there is a problem that it is difficult to set the fuel cut region sufficiently wide with just this system. That is, a normal fuel cut system is configured such that the accelerator pedal is completely opened and the throttle valve is closed so that the fuel cut is performed in a predetermined deceleration operation region (in this specification, this operation region is abbreviated as “large deceleration region”). To switch the valve from the open position to the shut-off position (the "shut-off position" in this specification includes not only the position where the fuel supply system passage is completely closed, but also the position where some fuel is allowed to flow). It has become. However, a closer observation of the driving state shows that the vehicle is running in an inertial or downhill condition where the accelerator pedal is not fully opened, that is, the throttle valve is returned to the closed position. In the operating region, the output torque of the engine may become substantially zero or less. Therefore, it is theoretically possible to perform the fuel cut even in such an operating region (in this specification, this operating region is abbreviated as “small deceleration region”). The fuel economy can be further improved as compared with the case where only the fuel cut is performed. However, in order to perform the fuel cut even in such a small deceleration range, it is necessary to detect the actual throttle opening by the throttle opening detection means and control the fuel cut valve carefully based on the detection result. Therefore, if the fuel cut range is expanded to such an area, in the conventional fail-safe system, the fuel cut valve may be held in the cutoff position if the throttle opening detection means fails, May cause stalls.

[Problems to be Solved by the Invention] The engine stalls when the throttle opening detection means used in the engine control system including the opening adjustment mechanism for adjusting the closed position of the throttle valve fails. It is possible to solve the problem that there is a possibility that it is difficult to expand the fuel cut area to the small deceleration area when trying to avoid performing an unreasonable fuel cut when the throttle opening detection means fails. The purpose is to solve.

[Means for Solving the Problems] In order to achieve such an object, the present invention, as shown in FIG. 1, is an opening degree adjusting mechanism (for moving the closing position of the throttle valve (2) ( 5) and throttle opening detection means (7) for detecting the opening of the throttle valve (2)
A valve closing position control means (37) for controlling the operation of the opening adjustment mechanism (5) to an optimum position according to the operating condition of the engine, using the value detected by the throttle opening detection means 7 as one input information; Fuel cut valves (15) and (16) for shutting off the supply system passage and a detection value of the throttle opening detection means (7) are used as one input information to define a fuel cut possible area, and the fuel cut is performed in that area. A fail-safe system applied to an engine control system, comprising a fuel cut control means (38) for switching valves (15) and (16) from an open position to a shut-off position, the failure detection means (A) When a failure of the throttle opening detecting means (7) is detected, the opening adjusting mechanism (5) is operated by the opening fixing means (B).
Is released from under the control of the valve closing position control means (37) and is operated and maintained at the opening position where the engine speed at no load is about 1000 rpm, and at the same time, the fuel cut inhibition means (C) is used. It is characterized in that the fuel cut valves (15) and (16) are fixedly held in the open position.

[Operation] With such a fail-safe system, when the throttle opening detection means (7) fails, the opening adjustment mechanism (5) is released from the control of the valve closing position control means (37). The engine speed at no load is about 1000rp
It is operated to the set opening position where it reaches about m, and then stopped. At that time, the fuel cut valve (1
5) and (16) are fixed to the open position, and the fuel cut is prohibited. As a result, the vehicle speed can be made to run without causing the engine speed to become too high and giving a feeling of runaway or causing an engine stall.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 2 to 5.

In the figure, 1 is a carburetor for an automobile engine, 2 is a throttle valve, 3 is a rotating portion of the throttle valve 2, and 4 is a spring for urging the throttle valve 2 in the closing direction. Reference numeral 5 denotes an opening adjustment mechanism (ISC) that locks the rotating portion 3 of the throttle valve 2 to adjust the closed position of the throttle valve 2, and 6 is provided in association with the opening adjustment mechanism 5. The idle switch (LLSW), 7 is a throttle opening detection means for detecting the opening of the throttle valve 2.

The rotating portion 3 is of a lever shape and is configured to rotate integrally with a support shaft 2b that supports the throttle valve body 2a. The opening adjustment mechanism 5 is provided with a feed screw portion 13 on the output shaft 12 of the DC motor 11 and a cap nut-shaped operator 14 screwed onto the feed screw portion 13.
When the motor 11 is operated, the operator 14, whose rotation is prohibited by a guide member (not shown), is screwed back and forth in the axial direction. And this D
The C motor 11 is driven by applying a DC voltage in pulses. Further, the idle switch (LLSW) 6 has a movable contact 6a provided so as to be able to advance and retreat together with the operator 14 of the opening adjustment means 5, and the movable contact 6a is brought into contact with and separated from the stationary contact 6b to turn ON / OFF. For switching the movable contact 6
a is supported by the output shaft 12 of the DC motor 11, and the stationary contact 6b is fixed frame 11a.
Held in. The output shaft 12 is held by the fixed frame 11a so as to be able to move forward and backward by a certain distance in the axial direction, and a spring (not shown) much weaker than the spring 4 is used to move forward (downward in the figure). ). Further, the actuator 14 screwed to the output shaft 12 is adapted to lock the rotating portion 3 at its tip 14a. Also, the throttle opening detection means 7
Is a potentiometer 8 for converting the opening of the throttle valve 2 into an analog electric signal, and the potentiometer 8
And an A / D converter (not shown) for converting the output of the above into a digital signal. Resistor 8a of potentiometer 8
5V voltage is constantly applied to the output terminal 8
An output voltage (0.1 to 4.9 V) corresponding to the opening of the throttle valve 2 is taken out from b. As a mode of failure of the potentiometer 8, there is a case where the output voltage becomes 0V due to disconnection,
There is a case where the output voltage becomes 5V due to a short circuit.

Further, reference numerals 15 and 16 are fuel cut valves provided in a main system passage 17 and a slow system passage 18 which are fuel supply system passages of the carburetor 1, respectively.

Further, 19 is an air bleed, and 21 is an air bleed control valve for opening and closing the starting end portion of the air bleed 19 to control the air-fuel ratio. The air bleed control valve 21 advances and retracts the pointed valve body 22 with respect to the valve seat 23 to change the opening area of the air passage formed between the valve body 22 and the valve seat 23, thereby reducing the air flow. Is controlled by the stepper motor 24.

Reference numeral 25 denotes a microcomputer system for controlling the opening adjustment mechanism 5, the fuel cut valves 15, 16 and the air bleed control valve 21 for performing idle speed control and throttle opening estimation control. Valve closing position control means 37, fuel cut control means 38, air bleed control valve (ABCV) control means, failure detection means A, opening fixing means B, and fuel cut prohibition means C.
Play a role as. The microcomputer system 25 includes a central processing unit 26 and a memory 27.
And interfaces 28 and 29. Then, at least the signal a from the idle switch (LLSW) 6, the signal b from the throttle opening detection means 7, the signal c from the rotation speed detection means 31, and the transmission state detection means (CNSW) 32 are provided to the interface 28. Signal from,
The signal e from the water temperature sensor 33, the signal f from the vehicle speed sensor 34, the signal g from the air conditioner switch 35, and the signal h from the O ₂ sensor 36 are respectively input, and
A drive signal i from the interface 29 to the opening adjustment mechanism 5, the fuel cut valve 15, 1
The signal j for 6 and the signal k for the air bleed control valve 21 are output. The rotation speed detecting means 31 is for detecting the rotation speed of the engine, and uses, for example, an ignition pulse. The transmission state detecting means (CNSW) 32 is for detecting whether or not the transmission state between the engine and the drive wheels is cut off.
A clutch switch that switches according to the on / off of the clutch, a neutral switch that switches when the transmission is shifted to the neutral position, and the like correspond to this. The water temperature sensor 33 is for detecting the cooling water temperature of the engine, and includes, for example, a thermistor that converts the water temperature into an analog electric signal and an A / D converter that converts the output of the thermistor into a digital electric signal. Be prepared. The air conditioner switch 35 is a switch for operating or stopping the air conditioner. In addition, O ₂ sensor 3
6 is a normal one provided in the exhaust pipe (not shown) existing upstream of the three-way catalytic converter, and when the air-fuel ratio of the air-fuel mixture is leaner than the reference value near the stoichiometric air-fuel ratio. No electromotive force is generated, and conversely, when the air-fuel ratio of the air-fuel mixture is on the rich side of the reference value, a high electromotive force can be generated.

The microcomputer 25 is programmed so as to operate according to the procedure schematically shown in FIG.

In the main routine shown in FIGS. 3A to 3E, first, in step 41, the failsafe execution flag YVTAFL is set to zero, and then in step 42, the idle switch (LL
Signal a from the SW) 6, signal b from the throttle opening detection means 7, signal c from the rotation speed detection means 31, signal d from the transmission state detection means (CNSW) 32, water temperature sensor 33.
From the vehicle speed sensor 34, the signal g from the air conditioner switch 35, the signal h from the O ₂ sensor 36, and the like. Next, it is judged whether or not the output voltage VTA of the potentiometer 8 of the throttle opening detection means 7 is above 4.9 V, and if it is above,
Proceed to step 46, and if not, go to step 44. In step 44, it is judged whether or not the output voltage VTA of the potentiometer is less than 0.1 V,
If it is less than this, the routine proceeds to step 46, and if it is not less than it, the increment counter CFAIL is cleared at step 45 and the routine proceeds to step 51. In step 46, it is judged whether or not the value CFAIL of the increment counter is counted up to 480 msec or more, and if it is, it proceeds to step 47 to set the fail safe execution flag YVTAFL to set fail fail. Issue a command to execute. When the value CFAIL of the increment counter has not reached 480 msec or more, the increment counter Q is cleared in step 48 and the process proceeds to step 51. The reason why the failsafe execution flag YVTAFL is not set for 480 msec even if an abnormality in the output voltage is found is to prevent the failsafe from being executed due to a temporary voltage change.
In step 51, the fail safe execution counter value YV
It is determined whether or not TAFL is maintained at zero. If it is zero, it is determined to be normal, and the routine proceeds to step 51 of the idle speed control routine II. However, if this counter YVTAFL is set to 1, Fail-safe execution routine VI
Go to step 91 of II.

When the routine proceeds to the idle speed control routine II, first, at step 52, the target speed NEGET is calculated. This target speed NEGET is the engine cooling water temperature, small lamp ON / OFF, heater ON / OFF, air conditioner
It is calculated according to various conditions such as ON / OFF.
In step 53, the value of the increment counter CL
Determine whether LISC (indicates the elapsed time from when the idle switch 6 is turned on. If the idle switch 6 is turned off, it remains zero and does not increase) is less than 5 seconds, and then step 5
In step 4, it is determined whether the vehicle speed SPD is, for example, 2.8 km / hr or more, and in step 55, the value of the increment counter
It is determined whether CFBDLY (indicating the elapsed time after ON / OFF change of the air conditioner or fuel cut is performed) is less than 3 seconds, and in step 56 it is determined whether the transmission system is in the transmission state. And each of these steps 53-56
If all of the conditions are ON, it is determined that the conditions for idle speed control are satisfied, and the routine proceeds to step 57. On the other hand, if any of the above conditions is YES, the routine proceeds to step 62 of the throttle opening estimation control execution routine III. When the process proceeds to step 57, it is determined whether the value CCDL (the elapsed time from the previously performed idle speed control) of the control cycle counter is less than 1 second, and the engine speed detected in step 58 is detected. Determine whether the absolute value of the difference between the number NE and the target speed NEGET is less than 20 rpm. If the conditions at steps 57 and 58 are both NO, at step 59 the ISC drive pulse width is calculated according to the magnitude of the difference in the number of revolutions,
Input the calculated value into the pulse width storage memory TISCOT and enter ISC
Issue a drive request. Then, in step 60, the value CCDL of the cycle counter is cleared, and in step 61, the match flag TA
SCTL (match flag used for TAS control, that is, throttle opening prospect control. TAS control is executed if set to zero, TAS control is not executed if set to 1) Memory throttle opening update routine is set to 1 Go to step 71 of IV.

On the other hand, if any of steps 53 to 56 is YES, the basic target throttle opening TAGET1 is calculated in step 62 of the throttle opening estimation control execution routine III. This basic target throttle opening TAGET1 is the basic water temperature map value
TAFT (target throttle opening water temperature map value when the air conditioner is OFF) and corrected water temperature map value for air conditioner TAAC (air conditioner ON
(Water temperature map value that determines the target throttle opening increase amount at the time)
Is the total value of. Next, at step 63, it is judged if the basic target throttle opening degree TAGET1 is equal to the stored value TAO (the value of the previous TAGET1). If they are not equal, the match flag value TASCTL is cleared in step 64, and if they are equal, the process directly proceeds to step 65 without passing through step 64. In this step 65, a new basic target throttle opening TAGET1 is set to the stored value TAO, and in step 66, the basic target throttle opening TAGET1 and the learning value TAIDG (actual optimum throttle opening (Learning value) and set the value. Next, in step 67, it is judged whether or not the coincidence flag value TASCTL is zero. If it is not zero, the process proceeds to step 71. If it is zero, in step 68 the final target throttle opening TAGET and the memory throttle opening MT are set.
It is determined whether or not the absolute value of the difference from A (throttle opening stored in the memory 23; updated appropriately in a memory throttle opening update routine IV described later) is less than 0.45 degrees. If the difference is 0.45 degrees or more, in step 69, the ISC drive pulse width is calculated according to the difference, the calculated value is input to the pulse width storage memory TISCOT, and the ISC drive request is issued. On the other hand, if the error is less than 0.45 degrees, the coincidence flag value TASCTL is set to 1 in step 70, and the process proceeds to step 71 of the memory throttle opening update routine IV. In step 71, it is determined whether the idle switch (LLSW) 6 is OFF. If it is not OFF, the actual throttle opening VTAZ (actual throttle opening detected by the throttle opening detecting means 7) is input to the memory throttle opening MTA in step 72, and if it is OFF, the memory throttle opening is opened in step 73. The degree MTA is updated by a certain angle (± 0.09 degrees; corresponding to the change angle of the throttle valve that is expected to change when ISC 5 is driven by one pulse) in the direction approaching the final target throttle opening TAGET. Go to step 74. In step 74, the match flag value TA
It is judged whether SCTL is zero or not, and if it is not zero (if there is a signal indicating that TAS control should be ended), the memory throttle opening MTA is set to the final target throttle opening TAGE in step 75.
If T is input and if it is zero, the process directly goes to step 76 of the throttle opening learning routine V without passing through step 75. At step 76, the value of the learning control cycle counter CISEC (elapsed time from the previous throttle opening learning control)
Is less than 1 second, and if it is less than 1 second, the fuel cut processing routine VI and ABC to be described later
It returns to step 42 through the V control routine VII. If it is 1 second or more, it is determined in step 77 whether a predetermined learning condition is satisfied. If the learning condition is not satisfied, the routine directly proceeds to the fuel cut processing routine VI. If the learning condition is satisfied, the learning value TAIDG is updated by ± 0.09 degrees in the direction toward the actual throttle opening VTAZ in step 78.
Then, in step 79, the final target throttle opening degree TAGET
Input the value obtained by adding this learning value TAIDG and the above-mentioned stored value TAO to, and in step 80, the value of the learning control cycle counter CISEC.
After clearing, the routine proceeds to the fuel cut processing routine VI, and returns to the step 42 through this routine VI and the ABCV control routine VII.

In step 51, the fail safe execution flag YVTA
When it is determined that FL is set, the routine proceeds to step 91 of the fail-safe execution routine VIII without executing the above routines II to V. When the process proceeds to step 91, it is determined whether or not the increment counter Q is less than 2 seconds, and when it is less than 2 seconds, the process proceeds to steps 97 through 92 and 93, and when it is 2 seconds or more, the step 94. Move to. In step 92, drive request information for driving the opening degree adjusting mechanism 5 in the closing direction with a duty ratio of 95% is input to the pulse width storage memory TISCOT. Then, in step 93, the value R of the increment counter is cleared. On the other hand, if it is determined that the time of 2 seconds or more has elapsed and the process proceeds to step 94, it is determined whether or not the value R of the increment counter is less than 0.8 seconds, and if it is less than 0.8 seconds, the process proceeds to step 95. If it is 0.8 seconds or more, go to step 96. In step 95, drive request information for driving the opening adjustment mechanism (ISC) 5 with a duty ratio of 37.5% in the opening direction is input to the pulse width storage memory TISCOT, and the process proceeds to step 97. On the other hand, in step 96, the pulse width storage memory TISCOT is cleared to prohibit the drive of the opening degree adjusting mechanism 5, and the process proceeds to step 97. In step 97, the actual throttle opening VTAZ input in step 42 is replaced with a value of 50 degrees. After that, the ON / OFF information of the idle switch input in step 42 is fixed to the information of OFF and the routine proceeds to the fuel cut processing routine VI.

The fuel cut processing routine VI executes the fuel cut valve 1 in both the large deceleration region and the small deceleration region described above.
5 and 16 are switched to the cutoff position to execute the fuel cut. More specifically, the fuel cut process in the large deceleration range is 1- 5 seconds after the engine is started.

1- Transmission of engine and drive wheels is maintained.

1-Engine speed NE is fuel cut release rotation NRT
Is greater than the value obtained by adding 200 rpm to.

1-Idle switch is ON.

When all of the above conditions are satisfied, the fuel cut valves 15 and 16 are switched to the shutoff positions to execute the fuel cut. And 1-the transmission between the engine and the drive wheels was cut off.

1-The engine speed is the fuel cut release speed NR
It became less than T.

1-Idle switch turned off.

When either of the conditions is satisfied, the fuel cut valves 15 and 16 are returned to the open position.

In addition, the fuel cut processing in the small deceleration area is 2 seconds after the engine starts.

2-Transmission between engine and drive wheels is maintained.

2-Idle switch is OFF.

2-Engine speed NE is fuel cut release rotation NRT
Is greater than the value obtained by adding 200 rpm to.

2-The actual throttle opening VTAZ is smaller than the throttle opening TASC specified by the engine speed. (When the idle switch is turned off due to the fuel cut in the large deceleration area, the actual throttle opening VTAZ is smaller than the value obtained by adding 3 degrees to the throttle opening TASC.) 2-The vehicle speed is 40 km / h or more. .

When all of the above conditions are satisfied, the fuel cut valves 15 and 16 are switched to the shutoff positions to execute the fuel cut. Then 2-the transmission between the engine and the drive wheels was cut off.

2-The actual throttle opening VTAZ has become larger than the value obtained by adding 3 degrees to the throttle opening TASC specified by the engine speed.

2-Engine speed NE is the fuel cut release speed
It was below NRT.

2-Idle switch turned on.

When either of the conditions is satisfied, the fuel cut valves 15 and 16 are returned to the open position.

Here, the fuel cut release rotation speed NRT is a map in which the optimum rotation speed according to the engine cooling water temperature is selected in advance. Further, the throttle opening TASC for small deceleration fuel cut is, as shown in FIG. 5, an optimum small deceleration throttle opening value (throttle opening at which the engine output becomes substantially zero) defined by the engine speed. It is selected in advance and mapped.

In addition, A following the above fuel cut processing routine VI
The BCV control routine VII is for opening and closing the air bleed control valve 21 based on the feedback signal from the O ₂ sensor 36 to maintain the air-fuel ratio of the air-fuel mixture supplied to the engine near the stoichiometric air-fuel ratio. .
The feedback control is not performed when the load is high. That is, the actual throttle opening VTAZ detected by the throttle opening detection means 7 is 4
When the temperature exceeds 0 degree, the feedback control based on the signal from the O ₂ sensor 36 is stopped and the air bleed control valve 21 is held at the fully closed position. And the actual throttle opening VTAZ is 37
When the temperature becomes equal to or lower than the frequency, the full-closed control at the time of the high load is stopped and the original feedback control is restored.

The interrupt routine shown in FIG. 3f interrupts the main routine every 40 msec, reads the value input to the pulse width storage memory TISCOT in step 101, and determines whether or not there is an ISC drive request. . Then, if there is the drive request, in step 102, a pulse voltage is applied to the opening adjustment means 5 with a pulse width equal to the value of the read pulse width storage memory TISCOT, and the DC motor of the opening adjustment means 5 is applied. 11 is operated for one pulse with the pulse width. On the other hand, if there is no drive request, the process returns to the main routine without operating the DC motor 11.

Next, the operation of this embodiment will be described. First, Fig. 3a
In the failure detection routine I shown in (1), it is diagnosed whether or not the throttle opening detection means 7 has a failure. If there is no failure, the output voltage VTA of the potentiometer 8 of the throttle opening detecting means 7 falls within the range of 0.1 to 4.9 V, so that the control always proceeds to steps 43 → 44 → 45. Therefore, the fail safe execution flag YVTAFL is not set. However, if the output voltage of the potentiometer becomes 4.9 V or more due to a short circuit or the output voltage becomes 0.1 or less due to disconnection, the process proceeds from step 43 or 44 to step 46. And
If such an abnormal state continues for 480 msec or more, the process proceeds from step 46 to step 47, and the fail safe execution flag YVTAFL is set.

As a result of the above diagnostic processing, while the value YVTAFL of the failsafe execution flag is maintained at zero without being determined to be a failure, the idle speed control routine II shown in FIG.
Throttle opening anticipation control execution routine II shown in FIG. 3c
I, memory throttle opening update routine IV, throttle opening learning processing routine V, fuel cut processing routine
VI and ABCV control routine VII are executed as intended, and the engine control system operates normally. That is, the idle speed control routine II is designed to converge the idle speed NE to the target speed NEGET by executing steps 58 to 60 every second. 5 seconds or less, 5 seconds or more when not idling or after idling, 3 seconds after NO / OFF change or fuel cut of air conditioner Not executed at no time. Further, the throttle opening expectation control execution routine III is configured such that the throttle opening is adjusted to an appropriate value in accordance with the operating state before the start when the idle speed control cannot be performed or when the idle speed control is stopped. It is for controlling expected position,
By executing this routine III, the opening adjustment mechanism 5 is driven at high speed so that the difference between the memory throttle opening MTA and the target throttle opening TAGET falls within an allowable value (± 0.45 degrees) or less. Further, by executing the fuel cut processing routine VI, the fuel cut is performed in the large deceleration region and the small deceleration region described above. Further, by executing the ABCV control routine VII, the air bleed control valve 21 is controlled to open and close based on the feedback signal from the O ₂ sensor 36, and the air-fuel mixture of the air-fuel mixture is maintained near the theoretical air-fuel mixture.

On the other hand, by executing the failure detection routine I, a failure of the throttle opening detection means 7 is found, and the step 47 is executed.
If the fail-safe execution flag YVTAFL is set in step 5, the fail-safe execution routine VI starts from step 51.
It will proceed to II, and failsafe will be executed. That is, in this case, first, for the first 2 seconds, the opening adjustment mechanism 5 is applied with a drive voltage to the effect that it should operate at a high speed (duty ratio of the drive pulse voltage is 95%) in the closing direction. As a result, the closed position of the throttle valve 2 is returned to the origin on the fully closed side. Next, for 0.8 seconds, the opening adjustment mechanism 5 is driven in the opening direction at a predetermined speed (driving pulse voltage duty ratio 37.5%). As a result, the closed position of the throttle valve 2 is shifted to an opening at which the engine speed at no load is about 1000 rpm. After that, since the operation of the opening degree adjusting mechanism 5 is prohibited in step 96, the closed position of the throttle valve 2 is maintained at that position. Further, in step 97, the throttle opening data is fixed to 50 degrees, and in step 98, the data of the idle switch 6 is fixed to OFF. Therefore, even if the routine shifts from this step 98 to the fuel cut processing routine VI, In addition, in the ABCV control routine VII, the air bleed control valve 21 is driven and held at the fully closed position because it is determined that the load is high.

Therefore, if such a fail-safe system is provided, even if the throttle opening detection means 7 fails, the idle speed of the engine is maintained at about 1000 rpm, which is slightly higher than the normal value. In addition, since fuel cut is prohibited, normal running can be performed without giving a feeling of runaway or causing an engine stall. Moreover, if the fuel cut is prohibited when the throttle opening detecting means 7 fails, in a normal case where there is no failure, a small deceleration range is obtained based on the value detected by the throttle opening detecting means 7. A wide range of detailed fuel cut control can be performed. In other words, if such a fail-safe system is not provided, the fuel cut area must be set narrowly in advance to prevent stalls. However, according to this system, the fuel cut area is released from such restrictions and the fuel is cut off. The cut area can be set as wide as possible and the fuel economy can be improved.

In the above embodiments, the case where the present invention is applied to the engine control system that also has the function of controlling the air bleed control valve has been described, but the present invention also applies to those that do not have such a function. The same is applicable.

EFFECTS OF THE INVENTION Since the present invention is configured as described above, it is possible to drive a vehicle without giving a feeling of runaway or causing an engine stall even when the throttle opening detection means fails. Moreover, the problem that the fuel cut area must be limited to a relatively narrow range in order to prevent the engine from stalling due to an unreasonable fuel cut when the throttle opening detection means fails is surely solved. It is possible to provide a fail-safe system that can improve economic efficiency. That is, for the first time, the configuration of the present invention, without any concern, not only controls the opening adjustment mechanism by using the detection value of the throttle opening detection means, but also a wide and gentle fuel cut over a small deceleration range. It becomes possible to control.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram for clarifying the present invention, FIG. 2 is a schematic configuration explanatory diagram showing an embodiment of the present invention, and FIGS.
Is an explanatory view for explaining a control procedure in the same embodiment,
FIG. 4 is a circuit diagram showing the throttle opening detection means, and FIG. 5 is a diagram showing the relationship between the throttle opening value for defining the fuel cut region and the engine speed. 1 ... Vaporizer 2 ... Throttle valve 5 ... Opening adjustment mechanism 7 ... Throttle opening detection means 15, 16 ... Fuel cut valve 25 ... Microcomputer system 37 ... Valve closing position control means 38 ... Fuel cut control means A ... Failure detection means B ... Opening degree fixing means C ... Fuel cut prohibition means

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kenichi Inoguchi 2-1-1 Taoyuan, Ikeda-shi, Osaka Daihatsu Industry Co., Ltd. (72) Inventor Shunichi Miyazaki 2-1-1 Taoyuan, Ikeda, Osaka Daiha Within Tsutsu Kogyo Co., Ltd. (72) Inventor Jun Umehara, 1-1, Kyowa-cho, Obu City, Aichi Prefecture Within Aisan Kogyo Co., Ltd. (56) Reference JP-A-58-57039 (JP, A) JP-A-59 -190448 (JP, A) JP-A-57-135242 (JP, A) JP-A-58-57039 (JP, A)

Claims (1)

[Claims] 1. An opening adjusting mechanism for moving a closed position of a throttle valve, a throttle opening detecting means for detecting an opening of the throttle valve, and a value detected by the throttle opening detecting means as one input information. The valve closing position control means for controlling the operation of the opening degree adjusting mechanism to the optimum position according to the operating state of the engine, the fuel cut valve for shutting off the fuel supply passage, and the detection value of the throttle opening degree detecting means. A fail-safe system applied to an engine control system, comprising: a fuel-cuttable area as one input information; and a fuel-cut control means for switching the fuel-cut valve from an open position to a shut-off position in the area. When a failure of the throttle opening detection means is detected by the failure detection means,
At the same time as opening the opening adjusting mechanism by the opening fixing means from the control of the valve closing position control means and operating and holding it to the opening position where the engine speed at no load is about 1000 rpm, A fail-safe system in an engine control system, wherein the fuel cut valve is fixedly held at an open position by a cut prohibiting means.