JP2000337184A - Control device of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out the fail-safe by detecting the reverse turn of an engine simply. SOLUTION: The trouble diagnosis result of an air flow meter having a reverse flow detection function is read (S1), whether the air flow meter has any trouble or not is detected (S2) and when no trouble is judged, the existence/ absence of the reverse flow is detected (S4) by whether the average value of the value subtracted the reverse flow detection value from the normal flow detection value of the suction air detected by the air flow meter is a negative value or not. When the generation of the reverse flow is judged, it is judged that the engine is operated inversely and the engine operation control such as an ignition control and fuel injection control is prohibited (S5).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an engine, and more particularly to a countermeasure when an engine reverse rotation occurs.

[0002]

2. Description of the Related Art If the engine reversely rotates by turning off a start switch or returning the rotation when the engine stalls, the operation of the engine is disadvantageously controlled. For example, as shown in FIG. 9, a generation cycle of a detection signal output at every predetermined crank angle is measured, and when a detection signal serving as a control reference is output, a predetermined cycle is determined based on the latest measured generation cycle. When the angle to the angular position is converted into time and detected to control the start of energization of the ignition coil and the end of energization (ignition timing), the reverse rotation of the engine causes The energization cutoff timing is detected earlier than the energization start timing, and the energization state may be continued.

In order to cope with such inconvenience at the time of engine reverse rotation, conventionally, the occurrence of engine reverse rotation is detected based on pulse signal output states from a plurality of crank angle sensors, and ignition control is prohibited when reverse rotation occurs. There is a configuration as described above (see Japanese Patent Application Laid-Open No. Hei 10-220330).

[0004]

However, the above-mentioned prior art requires a complicated detection method for detecting the occurrence of engine reversal based on the output patterns of a plurality of pulse signals, which results in a large calculation load. There is.

The present invention has been made in view of such conventional problems, and provides an engine control device capable of easily detecting occurrence of engine reversal and preventing occurrence of inconvenience. The purpose is to do.

[0006]

Therefore, according to the present invention, as shown in FIG. 1, an intake air amount detecting means for detecting an intake air amount by distinguishing between a forward flow and a reverse flow of intake air, An operation control prohibition unit for prohibiting operation control of the engine when the backflow of the intake air is detected by the intake air amount detection unit.

According to the first aspect of the present invention, when the engine reversely rotates, the piston descends when the exhaust valve is opened to take in air from the exhaust passage, and when the intake valve is opened, the piston rises to move toward the intake passage. The exhaust air causes a reverse flow of the intake air.

The reverse flow of the intake air caused by the reverse rotation of the engine is detected by intake air amount detecting means having a reverse flow discriminating function. The intake air amount detection means has a function of detecting the intake air amount on the upstream side and the downstream side of the intake passage, for example, and distinguishing between the forward flow and the backward flow of the intake air based on the detected values.

When the reverse rotation of the engine is detected by the reverse flow detection of the intake air amount, the operation control prohibiting means prohibits the operation control of the engine. In this way, the reverse rotation of the engine is easily detected. By prohibiting engine operation control and stopping the engine promptly,
Inconvenience can be avoided.

In the invention according to a second aspect, the operation control prohibiting means has a negative value obtained by averaging a value obtained by subtracting a reverse flow detection value from a forward flow detection value detected by the intake air amount detecting means. When the value of is reached, a reverse flow is determined, and the prohibition of the engine operation control is executed.

According to the second aspect of the present invention, the reverse flow of the intake air amount also occurs when a large intake pulsation occurs at a high load, but in this case, a small negative ( Since it is generated as a (backflow) wave, the smoothed intake air amount has a positive value, that is, a forward flow. In engine operation control, for example, fuel injection amount control, a value obtained by averaging the detected value of the intake air amount in response to the occurrence of intake pulsation is used. In the case where a means is provided, by using the value, it is possible to perform the fuel injection amount control corresponding to the intake air amount actually supplied to the engine.

On the other hand, when the engine reversely rotates, a substantially large reverse flow is generated as described above. Therefore, a value obtained by averaging a value obtained by subtracting the reverse flow detection value from the forward flow detection value as described above is negative. Value.

Therefore, when the averaged value becomes a negative value, it is determined that a substantial reverse flow of the intake air has occurred due to the reverse rotation of the engine, and the engine operation control is prohibited. In addition, the engine operation control can be prohibited by correctly detecting the reverse rotation of the engine.

The value averaged as described above is
This is a value used for normal engine control, and there is no need to perform special processing for detecting engine reverse rotation, so that engine reverse rotation can be easily detected.

The invention according to claim 3 is configured to include failure diagnosis means for diagnosing a failure of the intake air amount detection means, and the operation control prohibiting means is configured to detect the intake air amount by the failure diagnosis means. When the means is diagnosed as normal, the engine operation control is prohibited by detecting the backflow of the intake air.

According to the third aspect of the invention, when the intake air amount detecting means is out of order, the backflow cannot be accurately determined. Therefore, when the failure diagnosing means diagnoses that the intake air amount detecting means has failed, the engine operation control is not prohibited by detecting the backflow of the intake air, and the intake air amount detecting means is diagnosed as normal. Only at this time, the prohibition of the engine operation control by detecting the backflow of the intake air is executed.

In this way, erroneous detection of reverse rotation of the engine can be prevented, and prohibition of engine operation control based on the erroneous detection can be prevented. The invention according to claim 4 is characterized in that the engine operation control prohibited when the backflow of the intake air is detected is ignition control and fuel injection control.

According to the fourth aspect of the invention, when the engine reverse rotation occurs, the ignition control and the fuel injection control are prohibited, so that the adverse effects such as the continuous energization of the ignition coil and the erroneous fuel injection can be avoided.

[0019]

Embodiments of the present invention will be described below. FIG. 2 is a view showing an engine according to the embodiment. The engine 1 shown in this figure is a direct injection type spark ignition gasoline engine as described later. However, the engine is not limited to the direct injection type gasoline engine, but may be an engine that performs port injection.

In the engine 1, the air that has passed through the air cleaner 2 is measured by a throttle valve 3 and sucked into a cylinder via an intake valve 4. The electromagnetic fuel injection valve 5 is configured to inject fuel (gasoline) directly into the combustion chamber.
An air-fuel mixture is formed in the cylinder by the fuel injected from the fuel injection valve 5.

The air-fuel mixture is ignited and burned by spark ignition by an ignition plug 7 which is ignition-controlled by energization control of an ignition coil 6 provided for each cylinder, and combustion exhaust is discharged from the cylinder via an exhaust valve 8. After being discharged and purified by the catalyst 9, it is released to the atmosphere.

A control unit 10 incorporating a microcomputer controls the fuel injection by the fuel injection valve 5 and the ignition by the spark plug 7, and signals from various sensors are input to the control unit 10. .

As the various sensors, an air flow meter 21 for detecting an intake air flow rate Q of the engine 1, a crank angle sensor 12 for detecting an engine rotational speed N and outputting a position signal at every 10 ° crank angle, An oxygen sensor 15 for detecting the air-fuel ratio of the combustion mixture in response to the oxygen concentration, a throttle sensor 16 for detecting the opening TVO of the throttle valve 3, a water temperature sensor 17 for detecting the cooling water temperature Tw, and the like are provided. .

The control unit 10 determines a target equivalence ratio and a combustion mode (homogeneous combustion, stratified combustion) in accordance with the operating conditions detected by the detection signals from these sensors. Fuel injection amount,
While setting the injection timing, the ignition timing (ignition advance value) of the ignition plug 7 is set with reference to the ignition timing map individually set for each combustion method, and the ignition coil 6 is set accordingly. The power supply start time and power supply cutoff time are set.

Here, the crank angle sensor 12 is provided by T
A position signal is output at every crank angle of 10 ° with respect to DC, but as shown in FIG. 2, the position signal POS is configured to be omitted at a portion of BTDC of 60 °.

When the control unit 10 detects the missing portion based on the generation cycle of the position signal POS, it counts the number of subsequent generations of the position signal POS, and the count value matches the value stored in advance. Then, the position signal POS at that time is specified as the reference signal REF. The reference signal REF is used as a reference for measuring the power supply start timing and power supply cutoff timing for the ignition coil as described later. In the present embodiment, the position signal POS output at the position of BTDC 110 ° is the reference signal REF. As specified.

In the control of the power supply start timing and the power supply cutoff timing, the power supply cutoff timing (ignition timing) is determined from the engine load, the engine speed, and the like, and the power supply is controlled based on the power supply cutoff timing (ignition timing) and the power supply angle. The start time is calculated backward, and the angles from the BTDC 110 ° position to the power supply cutoff time and the power supply start time are calculated. And the BTD
The angle from the position C to the power supply cutoff timing and the power supply start timing is determined by the position signal POS from the reference signal REF.
The detection is performed by the angle control based on the count of the time and the time control based on the time conversion of the remaining angle, and the energization to the ignition coil is controlled (see FIG. 3).

The air flow meter 21 as a means for detecting the amount of intake air is constituted by a thermal air flow rate detecting device, and has a function of distinguishing between a forward flow and a reverse flow of intake air. It is configured as shown in FIG.

In FIG. 4, a flow meter main body 22 constituting a main body of the air flow meter 21 includes a winding part 24 around which a reference resistor 23 having a resistance value R1 is wound,
4, a terminal portion 25 integrally provided with a plurality of terminal pins (not shown), and a detection portion extending in the radial direction of the intake passage 3 from the distal end side of the winding portion 24. A holder 26,
It is roughly constituted by a circuit casing 27 described later.

As shown in FIG. 4, the detection holder 26 is configured to position a heating resistor 31 and the like, which will be described later, via an insulating substrate 29 at the center of the intake passage 30. The intake passage 18 is closed so as to close the mounting hole 18A of the intake passage 18.
The circuit casing 27 provided on the outer peripheral side of the device has a flow rate adjusting resistor 38, a differential amplifier, and the like, which will be described later, mounted on an insulating substrate (not shown) and incorporates them. The windings of the reference resistor 23 are connected to the terminals 28A and 28B.

The insulating substrate 2 attached to the detection holder 26
9 is removably attached to the detection holder 26, and as shown in FIG. 5, a heating resistor 31 and first and second temperature sensing resistors 32,
33 is formed on the main substrate portion 29A and the auxiliary heater 3
4 comprises a sub-substrate portion 29B on which a film is formed. Between the sub-substrate portion 29B and the main substrate portion 29A, from one side in the width direction to the other side (in the direction of arrow A in which the intake air flows). A slit 30 is formed.

The heating resistor 31 is formed to have a resistance value RH, and includes an intermediate resistor 31A and the intermediate resistor 3A.
It comprises first and second extension resistance portions 31B and 31C extending in opposite directions from both ends of 1A, and is formed so as to form a crank as a whole.

The current value of the heating resistor 31 is controlled by a current controlling transistor 42, which will be described later, and the insulating substrate 29 is also maintained at a constant temperature by heating so as to maintain the temperature at a constant temperature (for example, about 240 ° C.). It has become. The first and second temperature-sensitive resistors 32 and 33 are formed to have resistance values RT1 and RT2, respectively.
As shown in (2), heat is generated by applying a current from the battery voltage VB, and is cooled by flowing air, whereby the resistance value is reduced and the flow rate of the intake air is detected with high sensitivity.

When the intake air flows forward in the direction of arrow A, the first temperature-sensitive resistor 32 is cooled directly by the intake air, and the second temperature-sensitive resistor 33 is cooled by the heat-generating resistor 31. You will receive heat. As a result, the resistance value RT1 of the first temperature-sensitive resistor 32 decreases in accordance with the flow rate,
The resistance value RT1 of the temperature-sensitive resistor 33 does not substantially change.

On the other hand, when the flow of the intake air flowing in the intake passage 18 becomes the direction of the arrow B in the opposite direction, the second temperature-sensitive resistor 33 is directly cooled by the intake air, and the first temperature-sensitive resistor 33 is cooled. The resistor 32 receives the heat from the heating resistor 31. As a result, the resistance RT2 of the second temperature-sensitive resistor 33 decreases according to the flow rate, and the resistance RT1 of the first temperature-sensitive resistor 32 decreases.
Does not change substantially.

As a result, the resistance RT1 of the first temperature-sensitive resistor 32
And the resistance RT2 of the second temperature-sensitive resistor 33, it is possible to determine whether the flow direction of the intake air is the forward direction or the reverse direction.

The auxiliary heater 34 is formed in a film shape and heats the sub-substrate portion 29B of the insulating substrate 29 so that the heat from the main substrate portion 29A (the heat generating resistor 31) is removed.
To escape to the detection holder 26 via the The slit 30 prevents the first temperature-sensitive resistor 32 from being heated by the heat from the auxiliary heater 34, and the heat from the auxiliary heater 34 is applied to the first and second temperature-sensitive resistors 32 and 33 at the time of detection. Prevents joining. On the other hand, the auxiliary heater 34
Is connected between the emitter of the current control transistor 42 and the ground via a resistor 43, and the applied current is controlled (see FIG. 6).

A plurality of electrodes 3 are provided on the base end side of the insulating substrate 29.
5 are connected in line to terminals (not shown) on the side of the detection holder 26, and the heating resistors 3 are connected via the respective electrodes 35.
The first, second and third temperature sensing resistors 32 and 33, the auxiliary heater 34, and the like are connected to the respective electronic components provided in the circuit casing 27 to constitute a processing circuit for flow rate detection shown in FIG. .

FIG. 6 shows a processing circuit for detecting a flow rate according to the present embodiment. In FIG. 6, the current control circuit 36 controls the current value applied to the heating resistor 31 to maintain the temperature of the heating resistor 31 constant, thereby maintaining the temperature of the insulating substrate 29 at a constant temperature. A bridge circuit 40 comprising a temperature compensating resistor 37 and adjusting resistors 38 and 39;
It comprises a differential amplifier circuit 41 for outputting a difference from the connection points c and d of the bridge circuit 40, and a current control transistor 42 for controlling a current value applied to the connection points a and b of the bridge circuit 40. . The bridge circuit 40 is configured so that the products of the resistance values of the opposing sides are equal to each other. A connection point a between the heating resistor 31 and the temperature compensation resistor 37 is connected to the emitter side of the current control transistor 42 and the auxiliary heater 3.
4 and connected to the adjustment resistors 38 and 39 at a connection point b.
Is connected to the other end of the auxiliary heater 34 via a ground and a resistor 43.

Here, the temperature compensating resistor 37 is provided on the detection holder 26 in the vicinity of the heating resistor 31. The temperature compensating resistor 37 is not affected by the flow of the intake air. The resistance value RK changes only by the change.

The bridge circuit 40 thus configured
Is that the output from the differential amplifying circuit 41 becomes zero when in a balanced state, and when the balance is broken, that is, when the insulating substrate 29 is cooled by the intake air, the heating resistance 3
1 decreases, the resistance value RH of the heating resistor 31 decreases, and a voltage difference occurs between the connection points c and d.
The current control voltage Va is output toward the base. As a result, the current control transistor 42 is connected to the bridge circuit 4.
The bridge circuit 40 is returned to an equilibrium state by controlling the current applied to 0 to bring the cooled heating resistor 31 to a constant temperature.
At this time, the insulating substrate 29 can also return to a constant temperature.

Here, the current control transistor 42
Has a collector connected to the battery voltage VB, a base connected to the output of the differential amplifier circuit 41, and an emitter connected to a connection point a of the bridge circuit 40 and one end of the auxiliary heater. The current control transistor 42 controls the emitter current in response to the base current changing with the output (current control voltage Va) from the differential amplifier circuit 41. As a result, the current control transistor 42 controls the value of the current applied to the bridge circuit 40 to perform feedback control for keeping the temperature of the heating resistor 31 (insulating substrate 29) at a constant temperature.

Next, the detection processing circuit 44 includes a first
Flow detection circuit 45, second flow detection circuit 46, addition circuit 47, comparison circuit 48, inversion circuit 49, and selection circuit 5
0, and the detection processing circuit 44
The flow and the direction of the intake air are detected based on changes in the resistance values RT1 and RT2 of the temperature sensing resistors 32 and 33.

The first flow detection circuit 45 connects a first temperature sensing resistor 32 having a resistance value RT1 and a reference resistor 23A having a resistance value R1 in series between the battery voltage VB and the ground. The connection point e between the heating resistor 31 and the reference resistor 23A is connected to an adding circuit 47 and a comparing circuit 48 described later. Further, the first flow detection circuit 45 detects a change in the resistance value RT1 of the first temperature
Is output as the flow voltage V1.

Similarly, the second flow rate detecting circuit 46 is provided between the battery voltage VB and the ground, the second temperature sensing resistor 33 having a resistance value RT2 and the reference resistor 23 having a resistance value R1.
B in series with each other,
The connection point f between 3 and the reference resistor 23A is connected to the addition circuit 47 and the comparison circuit 48. The second flow rate detection circuit 46 detects a change in the resistance value RT2 of the second
2 is output as the flow voltage V2.

The output side of the addition circuit 47 is connected to an inversion circuit 49 and a selection circuit 50, and the flow rate addition signal (voltage V3) output from the addition circuit 47 is expressed by the following equation. V3 = V1 + V2 A selection circuit 50 is connected to the output side of the comparison circuit 48.
The comparison circuit 48 compares the first flow rate voltage V1 with the second flow rate voltage V2. When V1> V2, the flow of the intake air is in the forward direction, so that the direction of the voltage value V0 shown in FIG. The detection voltage Vb is output, and when V1 <V2, the direction of the intake air is in the opposite direction.

Based on the direction detection voltage Vb, the selection circuit 50 outputs the flow rate addition voltage V3 from the addition circuit 47 in the forward direction and the inverted flow rate addition voltage from the inversion circuit 49 in the reverse direction. V3 'is output to the control unit as an output signal Vout.

Next, the operation of detecting the flow rate of intake air in the detection processing circuit 44 will be described. Here, when the flow of the intake air is in the direction of arrow A (forward direction), the insulating substrate 29
The first temperature-sensitive resistor 32 located on the upstream side is cooled by the flow of the intake air, and the second temperature-sensitive resistor 33 located on the downstream side receives heat from the heating resistor 31. As a result, the first flow voltage V1 output from the first flow detection circuit 45 becomes larger than the second flow voltage V2 output from the second flow detection circuit 46, and the voltage from the comparison circuit 48 becomes higher. The forward direction detection voltage Vb having the value V0 is output to the selection circuit 50.

The addition circuit 47 adds the input flow voltages V1 and V2 and outputs the result as a flow addition voltage V3 to the subsequent selection circuit 50 and the inversion circuit 49. The inversion circuit 49 outputs the inverted inversion flow addition. The voltage is output to the selection circuit 50 as the voltage V3 '.

Here, in the selection circuit 50, the comparison circuit 48
The selection is made between the flow addition voltage V3 output from the addition circuit 47 and the inverted flow addition voltage V3 'output from the inversion circuit 49 based on the direction detection voltage Vb from. Since the signal is a signal indicating the forward flow having the voltage value V0, the flow addition voltage V3 is selected, and the flow addition voltage V3 which becomes the forward flow from the output terminal to the control unit is output as the output signal Vout.

On the other hand, when the flow of air is in the direction of arrow B (reverse direction), the second temperature-sensitive resistor 33 located on the upstream side of the flow in the shape of the insulating substrate 28 causes the flow of air to flow. Is cooled by the first temperature-sensitive resistor 32 located on the downstream side.
Receives heat from the heating resistor 31. As a result, the second flow rate voltage V2 output from the second flow rate detection circuit 46 becomes the first flow rate voltage V2 output from the first flow rate detection circuit 45.
The comparison circuit 48 outputs to the selection circuit 50 a direction detection voltage Vb in the reverse direction which becomes larger than 1 and becomes zero in voltage value.

In addition, in the addition circuit 47, the flow rate addition voltage V3
Is output to the selecting circuit 50 and the inverting circuit 49, and the inverting circuit 49 outputs the inverted inverted flow rate addition voltage V3 ′ to the selecting circuit 50.

Further, in the selection circuit 50, the comparison circuit 48
The selection is made between the flow addition voltage V3 output from the addition circuit 47 and the inverted flow addition voltage V3 'output from the inversion circuit 49 based on the direction detection voltage Vb from. Since the signal is a signal indicating a reverse flow having a voltage value of zero, the reverse flow addition voltage V3 'is selected, and the reverse flow addition voltage V3', which becomes a reverse flow from the output terminal to the control unit, is output from the output signal Vout.
Output as

Thus, the control unit 1
At 0, the flow rate and flow direction (forward flow, reverse flow) of the intake air can be accurately detected based on the output signal Vout.

As described above, detection of engine reverse rotation and fail-safe control at the time of occurrence of reverse rotation are performed using the air flow meter 21 having the function of detecting forward flow and reverse flow separately.

FIG. 8 shows a flowchart of the detection of the engine reverse rotation and the fail-safe control when the reverse rotation occurs. In step (denoted as S in the figure, the same applies hereinafter) 1, a failure diagnosis result of the air flow meter 21 is read. As the failure diagnosis, for example, as a first determination method, a change width ΔUs of the output voltage Us of the air flow meter 21 is calculated under an operating condition that generates intake pulsation of a predetermined level or more,
It is determined whether or not the change width ΔUs is equal to or greater than a predetermined threshold. If it is equal to or greater than the threshold, it is determined that the air flow meter 6 is normal because the output voltage has changed according to the intake pulsation. Is smaller than the threshold value, there is a method of determining that the air flow meter 21 has failed because the output voltage has not changed in accordance with the intake pulsation. As a second determination method, when the output voltage of the air flow meter 21 is not a value equivalent to the intake air amount 0 when the engine is determined to be operating, it is determined that the air flow meter 21 is normal. However, when the intake air amount is equal to 0, there is a method of determining that the air flow meter 6 has failed. In addition, there is a third determination method for determining a failure when both of the first and second determination methods determine that a failure has occurred, and these methods may be used as appropriate.

In step 2, it is determined whether or not the air flow meter 21 has failed based on the failure diagnosis result (diagnosis flag or the like) of the air flow meter 21 read in step 1, and it is determined that the air flow meter 21 has failed. In this case, the process proceeds to step 3 without prohibiting the engine operation control based on the detection of the engine reverse rotation, and the engine operation control such as the ignition control and the fuel injection control is continued.

In the determination of step 2, the air flow meter 21
Is determined to be normal, the routine proceeds to step 4, where it is determined whether or not backflow has occurred based on the intake air amount detected by the air flow meter 21. Here, as the intake air amount, a value obtained by averaging the air flow meter detection value (detection voltage) as in the normal engine operation control is used, but as described above, the forward flow detection value of the air flow meter 21 ( The detected value of the backflow (reversed flow added voltage V3 ′) is output as an inverted negative voltage with respect to the flow added voltage V3), and the value obtained by subtracting the detected value of the backflow from the detected value of the forward flow is averaged. The converted value is used. When the value thus averaged is a positive value (voltage), the flow is determined to be forward flow, and when the value is negative value (voltage), the flow is determined to be reverse flow.

When it is determined in step 4 that the flow is forward, the process proceeds to step 3 and engine operation control such as ignition control and fuel injection control is continued. However, when it is determined that the flow is reverse, the engine is reversed. Then, the process proceeds to step 5 to inhibit engine operation control such as ignition control and fuel injection control.

As a result, it is possible to prevent the engine from being stopped quickly, and to prevent the ignition coil from continuing to be energized and to prevent the fuel from being erroneously injected. Further, by detecting the reverse flow of the intake air amount, it is possible to easily detect the reverse rotation of the engine without performing complicated arithmetic processing such as the one based on the signal pattern of the crank angle sensor. By using the converted intake air amount for backflow detection as it is, there is no need to perform special processing for engine reverse rotation detection, and when backflow occurs during intake pulsation at high load (averaged value Is a positive value), and the reverse rotation of the engine can be accurately detected.

When the air flow meter 21 is out of order, the backflow cannot be accurately determined.
The prohibition of the engine operation control by the backflow detection is not performed, and the prohibition of the engine operation control by the backflow detection of the intake air is performed only when the airflow meter 21 is diagnosed as normal. And prohibition of engine operation control based on the erroneous detection can be prevented.

[Brief description of the drawings]

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

FIG. 2 is a system configuration diagram according to an embodiment of the present invention.

FIG. 3 is a time chart showing how a crank angle position is detected in the embodiment.

FIG. 4 is a longitudinal sectional view showing a state in which the air flow meter according to the embodiment is attached to an intake pipe.

FIG. 5 is a plan view showing a heating resistor and first and second temperature-sensitive resistors formed on an insulating substrate of the air flow meter.

FIG. 6 is a diagram showing a configuration of a flow rate detection processing circuit of the air flow meter of the above.

FIG. 7 is a characteristic diagram showing a fluctuation and a direction of a flow rate of intake air in the embodiment.

FIG. 8 is a flowchart of detection of engine reverse rotation and fail-safe control when the reverse rotation occurs in the embodiment.

FIG. 9 is a time chart showing a conventional problem.

[Explanation of symbols]

 1 Engine 6 Ignition coil 7 Spark plug 10 Control unit 12 Crank angle sensor 13 Air flow meter

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI theme coat ゛ (reference) F02P 11/02 303 F02P 11/02 303Z F term (reference) 3G019 AA09 AC00 CA11 CB04 CB26 DA05 3G084 BA13 BA16 CA09 DA28 FA07 FA10 FA13 FA29 FA33 FA35 3G092 AA01 AA05 AA06 BA08 BB02 EA14 EB01 FB05 FB06 GA20 HA01Z HA06Z HB01X HC08X HD05Z HE01Z HE03Z HE08Z 3G301 HA01 HA04 JA34 JB09 JB10 KA11 LA03 PE03 PE03 PE03 NE03 NB04

Claims (4)

[Claims] An intake air amount detecting means for detecting an intake air amount by distinguishing a forward flow and a backward flow of the intake air; and controlling the operation of the engine when the reverse flow of the intake air is detected by the intake air amount detecting means. An engine control device, comprising: a driving control prohibiting unit that prohibits the operation. 2. The method according to claim 1, wherein the operation control prohibiting means is configured to generate a negative value when a value obtained by averaging a value obtained by subtracting a reverse flow detection value from a forward flow detection value detected by the intake air amount detecting means becomes a negative value. 2. The engine control device according to claim 1, wherein it is determined that the flow is reverse, and the engine operation control is prohibited. 3. A failure diagnosis means for diagnosing a failure of said intake air amount detecting means, wherein said operation control prohibiting means is diagnosed by said failure diagnosing means that said intake air amount detecting means is normal. 3. The engine control device according to claim 1, wherein prohibition of engine operation control is performed by detecting the backflow of the intake air. 4. The engine according to claim 1, wherein the engine operation control that is prohibited when the backflow of the intake air is detected is an ignition control and a fuel injection control. Control device.